Review: Bent Audio Tap Linestage


Category: Preamps

Before, I get to the details of reviewing the Bent Audio Tap Linestage, I first would like to give a context regarding what my linestage reference of the last three years has been in order to "set the stage" so this review would be the most helpful to the members reading it.

My reference over the last three years has been the Placette Audio Dual Mono Active Linestage. It replaced a ML-32 reference preamp in my system. I had auditioned six different preamps/linestages, half were tubed - half were solid state ranging in price from $6000.00 to $16000.00, until I finally heard the Placette Active in my system and found what I was looking for sonically. It offered, compared with the other pieces in my home auditions, the following sonic virtues:

1) No noise floor at all. Music just "floated" out of a totally black background.
2) A great soundstage, front to back - side to side, with the best center fill and layering I ever had in my system.
3) Precise microdynamics and details without being what I would call "dry" or "etched" at all.
4) Excellent extension on both the top and bottom with great slam in the lower bass.
5) Natural tone/timbres, very important to me because I listen almost totally to acoustic jazz.

Not bad stuff! However, being the curious audiophile that I am, I had read about a few new linestages that had come out the last couple of years and decided to listen to what some of the best designers were up to now. This time around I auditioned a highly regarded solid state,tubed, and transformer based units. Even though the solid state ant tubed pieces were almost twice as expensive as my Placette, and they have their virtues, I did not find them to better the Placette in the above mentioned areas. Different but not better for my ear's and personnal taste.

That's the context, now on to the review. The Bent Tap Linestage is the child of John Chapman and his company Bent Audio out of Canada. I would like to share John is one of the great gentleman/designers of high end gear and is a true pleasure to talk and to do business with. His pieces are purchased direct, with a 30 day trail period with full refund if one is completely not satisfied.

At this point in time there has been a full review on the Tap Linestage on POSTITIVE FEEDBACK ONLINE website by Bruce Kinch and on SIX MOONS website there is what they call a "pre-view", along with one of SIX MOONS reviewers, Les Turoczi, who considers the Tap Linestage one of the "favorite discoveries of 2006" and has made it his new reference linestage in his system.

The above mentioned reviews, along with information on the Bent Audio website, will provide excellent background information on the topic of passive preamps/linestages and specificly on the issue of transformer based passives compared to Vishay resister based approachs. By the way, the Placette Active is a Buffered Vishay based passive linestage that gives no gain, but eliminates any concerns with impedance matching the front end with the down stream amps.

I never get into lengthy details regarding engineering or parts, that is all provided by the Bent Audio website, however I always comment on build quality and looks before I get to the the most important part the sonic performance. The Tap Linestage has a "cool modern" look to it, but it will never be the "eye candy" that my Pass Labs or Accustic Arts pieces are to me. The front has angled sides and sits atop a 1" slab of clear acrylic which has been routed out to securely mount the twin transformers. Inside high quality Arlon circuit boards, ribbon cables, and custom OCC copper wire sourced from Neotech speak highly of the construction of this piece.

Now, to the most important part of any review, the sonic performance of the piece being evaluated. In the following areas the Tap and PLacette active were, at least for me in my system, indistinguishable:
1) Total black background, no noise floor, music just "oozes" out of the system.
2) Both provide the best soundstage and layering of any linestage I have ever had in my system.
3)Macrodynamics are present and powerful, but intergrated in the overall "fabric" of the music.

Were the two linestages start to part sonic company is revolving around to key sonic areas, tone/timbres and image density of players in the sound stage.

I find that the Tap to be slightly "warmer/fuller" then the Placette Active in overall timbres, what many listeners would refer to as the "magic of tubes", mind you, not "fat/euphonic" but more "velvety" then the "silkyness" of the Placette. It reminded me when I went from an Edge NL-10 to a pair of Pass Labs XA-100's, both great amps, but I found the XA-100's to be subtly more what I call "organic/musical". Another verbal stab at it would be to say that the Placette Active has "razor sharp" leading edges and the Tap is a little more "rounded off" but has more body and decay then the Placette Active.
The Placette Active never sounds "etched, dry, or overly analytical, but a little less "sweet" then the Tap. They both offer beautiful sonic pictures and what you would like would be very much decided by your personnal taste and what type of system synergy you would end up with in your rig.

The other sonic difference that I noticed was in the area of image density. The Tap kicked it up a notch in comparsion to the Placette Active regarding the density of images, not the size or air around the individual players, but how "real" they sounded in the stage. Again, both linestages are quite terrific regading this sonic aspect, but the Tap gives more in this area then the Placette Active.

So, is there a winner or loser between this linestages, I don't think so, there both reference level in their performance. As I always say at this level of gear it comes down to personnal taste and system synergy. There's always very small but real differences in gear, but the final voicing of any system finally comes done to matching this tiny sonic bits together to get what we are listening for in the pleasure of the music we care about.

The Bent Tap is my new reference linestage for the reasons stated above. Both the Tap and Placette Active are great performers, terrific bargains for what they sell for, the Tap $3000.00, the Placette Active $5000.00, when you think they compete with any linestage on the market today and both John Chapman and Guy Hammel are great gentleman to work with, you might put both on your audition list if your seeking out a new linestage. Which one you would like better truly would come down to personnal taste/system synergy, so really won't know till your try it in the context of your own rig.
teajay
Drubin, it's probably because your source doubles output voltage into balanced. My CDP, for example, puts out 2.1V into RCA and 4.2V into XLR. You might be comparing to non-differential preamps.
Darkmebius,
I believe John Chapman of Bent Audio recommends burn-in at volume 31, and this should take care of the other taps. But I guess if one is really fastidious, then burining in at each step would be best!
Teajay, in order to use the TAP, what are the required specs from the associated components like source(cdp) and the amp if running balanced?
Audphile1, I know the Tap is very forgiving of impedences in single ended mode, so I would expect it not to change drasticly when used balanced.

However, the best thing to do is to contact John Chapman, just talked to him day, who's a great gentleman and would answer your question with total expertise, that I lack in this matter. Give him a call.
Teajay, yep...I did just that! John explained how the unit blends into the system and what is needed for it to work best. So far it seems like it will be a good fit with the components I have. It should work well with my amp, X250.5, since the specs are basically the same as your amps. The only ? I had was w/r to the cd player output. John confirmed it should be fine.
I have few things going right now, so once I work all this out, I think I will give the TAP a try.
I am still hesitant to change from the tubed pre to solid state....haven't used any solid state preamps in about 10 years. Now using ARC LS-25(original, not MkII).
is it correct to describe the TAP as solid state? It's passive so it has neither tubes nor transistors. Same for resistor-based passsives.
Drubin, may be not, but the tube linestage I am using now will no longer be there between the cd player and the solid state amp, which pretty much makes the whole thing solid state as far as I'm concerned.
Drubin, I agree the Tap is neither solid state or tubes, that's why passives are alternatives to both types regardless if their transformer or resister based.

Did you ever come to any conculsions regarding the Tap in your system? It would be great if you would share what your impressions of it were in the context of your system.
Drubin, please post your impressions once you are done evaluating.

What I meant by solid state is that the tubed linestage I am now using, if I replace it with TAP, then it's a solid state system pretty much. My cd player and amp are solid state. I posted it before, but something happened and the post did not appear. If it appears, sorry for the dup.
"03-06-07: Drubin
is it correct to describe the TAP as solid state? It's passive so it has neither tubes nor transistors. Same for resistor-based passsives. "

I don't think so.

TVC's are best described by the primary component that does their job, the transformer. For that reason, the best description might be simply "magnetic".
Tedmbrady, how's the experiementing with your different speakers/gear with the Tap been going? Are you missing in some way your Modwright tubed preamp?

It would be great to hear from you regarding what your recent impressions have been regarding the Tap, if it's a keeper for you or maybe not your sonic cup of tea. Let us know.
My TAP evaluation is on temporary hold. I just discovered that my Sason speakers present an interesting load (high impedance for the most part) that is adding to the Krell's clinical sound, and thus to my TAP eval. I need to either insert a well-heeled tube amp in this process (like an Atma-Spehere M60 or MA1) or go in another direction with speakers (the leader being ATC actives and chuck the whole amp idea). John has been very understanding and insisted I keep the TAP until I can eval it with the right gear. I can't let this linger, though, regardless.

I'll report back soon. As of now, the TAP is still a close no. 2 to the Modwright in MY system, but I've explained why.
Well, a couple of updates, one of which is very interesting and concerning:
1) The uninteresting one: I bought a McCormack DNA-500 amp and mated it last night with my Modwright pre. Too much humm and buzz, and the dimmers in my house drove it crazy. I inserted the TAP and all is dead quiet, even using the TAP in rca SE mode (which you need to do if using balanced cables to the DNA-500 and yet rca's to the subs). Dead quiet and very musical so far. Yes! John's been very understanding about my eval, but maybe I've found a good synergy.......oh,
2) Interesting and concerning one: John Chapman has been terminated by S&B as a TX102 supplier!! Some sophomoric misunderstanding about a UK TAP-X review (read about it on John's Audio Circle forum) and S&B's unwillingness to have John compete with them on their new pre?? Looks like he'll fire up a new non-S&B TAP in the summertime.

More to follow....
Artemus5 sir, I am sorry for such a long response delay. Here sir, is my opinion of Supratek vs mfa. Whom, as I understand it recently aquired Bent, to whom they had been supplying their transformer's. I think that this testifies to their respect for Bent.I recieved the sauvignon in January after having listened to the mfa for a while, which in my opinion is a fab piece. To my suprise my real response was the total oposite of my expection. To my ears, and in my system, meaning room included, I found the supratek far superior in every way. What we must understand is that passive does not drive, a well designed passive passes all of the information in tact. now I must admit that tvc passive is somewhat of an exception in it's execution and presentation of the performance. If your amp's are sensitive and your and speakers reasonably effecient then a passive can really shine in it's ability. That being said a great active in my opinion can present an atmasphere, A halls presence, a place, an environment,ie Carnige hall, or the chicago symphony hall. Now that is not to take away from the savvy of those that prefer passive, but symply provides another ligitimate avenue of preference. So astounding was the sauvignon, that within a week I sold it and ordered the Cabernet dual. Well, I just recieved it, and out of the box, it's superiorty to anything that I have ever experienced was immediately evident. It did everything that my MFA passive did, and much much more. I am supremely happy, and the new metronome kalista transport brought my audiologic 34mxl dac to a level of performance That I did not know it to be capable of, as good as it was. And the Cabernet pushed my Magico reference's to a new level of magic. I have over the years owned many passives, from the great Rick Schultz attenuators to the reference line. So I have had quite a bit of experience with them. They will beat most actives in many areas. but the
Cabernet does and I must quantify this stament by adding again, (in my personal opinion) all that the best passives can do, and all that the very best active's can do.
The Cabernet is the crowning glory of my system.This commentary is no judgement on the choice of anyone else.
Very interesting review, thank you.

As always, this begs the question -- for me, at least -- of how it is possible that an active stage can deliver "atmosphere" that an excellent passive does not. Is the atmosphere real, such that the active is doing a better job of extracting (or passsing along) what is on the recording? Or is it an artificial by-product of the active's circuitry? I don't suppose there is an answer to this question.

Am I correct that active pre-amps add gain before they attenuate? So the mechanism in play is to have a more robust signal to attenuate. In addition to whatever impedence differences an active device presents.
Drubin sir, I am not very technical, so when it comes to white paper, I am not your man. But here are my thoughts, I respectfully reiterate(my thoughts). What I think may be happening with atmosphere, is that the ability of a extremely well designed active preamplifier, such as the very,very quiet supratek Cabernet dual, amplifies and presents more information then many active circuits are not capable of, information that one may not conciously consider, such as the microsonic artifacts in a room that give clues of atmasphere that might otherwise escape ones attention. For example, notice how that one may listen to a recording with say, preamp A, then insert preamp B and suddenly clues buried come forth. This is not to imply that a well designed passive cannot present this information, It has simply been to my experience and to my ears that the dynamic ability of a superbly designed active to propel the same information with a sonic turbo can make that information more visable sonically, and emotionally more envolving. This is no attempt to sound scientific, or to sell my preference. Simply my personal experience and personal pleasure. But I must say that it takes a rare breed of active circuit to pull off this allusion . To those of you in the passive camp, a salute of respect to you. Enjoy music.
I would like to address a couple of different items with this post.

1) In a past conversion with John Chapman, he shared that S&B was very annoyed that he would not jackup the price of the TAP for the North American market, so they could ask for a very high retail price in the European market for the Tap under their Music First banner. I have so much respect for John, both as a designer/manufacturer and a businessman who wants to make a fair profit, but not proposely inflate the price of his pieces for shear greed. My hunch is S&B thinks they screwed John by not supplying their transformers anymore, I just think they have put egg on their own greedy faces, and John is shown to be the first class gentleman that he is. I'm sure he'll just find another company to build his trannies or just build them himself.

2) Audioezra, congratulations on your new Cabernat preamp and your Kalista transport! I know your were very excited to get them and put them into your system, so I'm very glad they are giving you the pleasure of the music you were seeking. I'm still looking forward to coming over with Bob to your home and having a great time hearing your reference system.

3)Drubin, I have tried at least four very highly regarded tube linestages, the last audition was the Monbrisson Shinto Labs, and have found in my system and for my personnal taste that they offered no sonic virtues over either the Placette Active or my Bent Tap. I still think many, not all by any means, offer a somewhat euphonic coloration that some people love and find to be more "musical" to their ears or in the synergy of their systems. That's way it's so important to try any piece of gear in your system in your home environment.
"I still think many, not all by any means, offer a somewhat euphonic coloration that some people love and find to be more "musical" to their ears or in the synergy of their systems."

Excellent point Teajay. I have a K&K TVC that uses S&B TX-102 MkI transformers and I must say thay it is by far the best preamp I have had in my system. Previously I was using a Joule Electra LA-100 MkIII which I feel is a very musical preamp and quite capable of delivering it's fair share of atmosphere and realism. The K&K doesn't give an inch in that regard and surpasses the Joule in transparency, detail, and clarity.

I have no doubt that some active preamps can achieve a level of transparency, detail, and clarity on par with a passive preamp. However, to do so would mean a significant investment. In fact I find it interesting that some tube preamp designers, are trying to voice their active preamps to be more neutral and transparent which to me defeats the purpose of a tube design. Personally, in buying a tube preamp I would expect some type of coloration which would provide a unique sonic signature and hopefully one that would satisfy my preferences.
What a nasty piece of business that was by S&B. I know how much time John invested in the development of the TAP but I also know that John won't give up and it was not for naught. My sympathy to John and the customers that will have to wait.
Hi Guys

I posted the following thread in AudioCircle but thought it worth repeating here because I need some feedback on what amplifier gain would be best to drive the TAP. It seems that impedance match, source voltage and speaker sensitivity are all factors that contribute to the TAP's sonic virtues:

"It might be interesting to find out the nature of your amplifier that you are matching with your Bent TVC. My amplifiers are the superb CIAudio D*200 Monos with 26 dB (XLR). With my SB3, CDP, radio tuner or TV source I find myself utilising the volume between the 20 and 30 range, giving me satisfactory sound levels. However, in the rare occasion when I play a SACD track or DVD movie (like "The Mission" starring Robert De Niro) I find myself cranking it up to 31 (unity) and occasionally when the dialogue softens, it is at maximum 34!! As you know, the 6 DB automatically engages for the TAP beyond 31. While 90% of my listening raises no issues with a 26 dB amplifier gain, it would be nice to have more headroom with DVDs. I wonder if any of you are experiencing the same concerns? Would appreciate your views and observations!"
Denjo, in my system I only have a FM tuner and my digital front end as sources into the Tap. I would say that 99% of the time the volume setting on the Tap is between 25 to 29 to get my total system to "snap" into total focus and present the best sonic picture for that piece of music. So, I never have encountered any concerns with volume settings with the Tap in my system.
My McCormack DNA-500 and TAP, with either the Modwright modded 3910 tubed stage, or the modded RWA Squeezebox3/Dac combo is usually running around 25-28. That fills a 3500 cubic foot room with anywhere from perfect to loud music. My current speakers are 87-88 db efficient, so not a hi-efficency speaker by any means.
Denjo, gain on your CI amps is on the low side. I wonder if it is switchable (it is on many amps) or if Dusty could goose it for you.
Thanks guys! Glad to know i'm not the only one pushing my Bent TAP close to its maximum!
Teajay: Like you, most of my listening is of the SB3 and FM tuner. So, most times it presents no problems. Out of curiosity, what senstivity are your speakers?
Tedmbrady: Now that sounds like a superb combo. I've always liked the DNA-500. I think they are 29 dB gain, right. 6Mooner Lez uses the same system as you and is happy as a lark!
Drubin: Thanks for the suggestion. The D*200s are UCD Hypex modules (tweaked by Dusty) but the default gain is 26 dB. I've read that converting it to 32 dB introduces some feedback and sonically compromises the sound. Problem is, I have an active preamp whicvh I like to switch back to once in a while. The 32 dB gain will be too much for my active pre.
I don't have a TAP but a DIY using TX102 mk3's. With a Talk Thunder 3.1B putting out 4.2V into XLR (<100 ohms) and dual Plinii SA100's with 38db gain (seemed almost double when bridged), the knob sits between quarter and half way. The speakers are 91 db Genesis 350's that have dynamics to make horns jealous and their own bass amp. At full volume, they would fill a stadium. The beauty of it is, even when cranked, it's dead quiet until I hit play.
FWIW - I had the chance to demo a TAP and it worked great with My Krell FPB-300C [26dB gain/100kOhm/2.71Vrms input specs] and my Legacy Whispers [95dB @ 2.83 v/m]. Now the Whispers do come with a speaker processor of which I don't know the in/out specs, but I tried it without this processor and the levels were quite acceptable...and the system absolutely dead quiet. My room is also 3500+ cubic feet, and my player was an esoteric DV-50 [2.2v/600 Ohm output].
Recently auditioned Sanders ESL amplifier (www.sanderssoundsystems.com) and am very impressed! Interestingly, the Sanders amp is rated 26 dB gain, which is the same as my CIAudio D*200 Monos, but with the Sanders my volume on the TAP is much less for the same sound pressure. I find that I am usually operating between 15 and 22!! How do you explain this?
Perhaps the new amp delivers more current for the same power???

Oddly, I once went from 1200w/ch to 350w/ch with no real difference in volume level, but a great improvement in sound quality with the 350w amp.
Just wanted to share that on this last Sunday afternoon my girlfriend, she's a musician with great ears, and I did an audition comparing the Tap to a very highly regarded SS preamp that retails for $6000.00.

I have tried before on other occasions two tube preamps to see if they offered something the Tap did not in my system, and neither replaced the Tap.

Well, the SS preamp offered great details, dynamics, big soundstage, and offered a silky/smooth approach to timbres. Not bad, but the Tap still had all those sonic virtues and added a liquidity/easyness, lower noise floor, and more natural timbres in my system. I find it amazing that many audiophiles still believe that passives don't do dynamics like an active, well maybe the older designs, but the TVC's and buffered passives don't suffer in this area at all as far as I can tell!

I talked to John Chapman today and he hopes to be up and running building new Taps at the end of the summer. I hope so because it offers so much performance, build quality, and features at such a reasonable price.
Teejay, interestingly I did the same and swapped the Bent TAP for my active preamp (highly modified). After about an hour or two, I found that the active pre was just unlistenable. The active pre sounded better I thought with my CIAudio D*200 monos as I felt the TAP through the D*200s sounded closed in and less dynamic. You will see from my earlier thread that I was concerned that through the D*200s, I was almost playing the TAP at maximum volume. When I hooked up the Sanders ESL amplifier, I was amazed that it synergised so well with the TAP. The sound was dynamic, soundstage was superb (not only deem and wide but high as well!) and the bass coming from my Thiels was simply a revelation! I did not know my Thiels could pump out so much bass! This leads me to the conclusion that system synergy is very important. Comments you read about the TVC being less dynamic, lean sounding, etc I suspect are due to the fact that the amplifier is not powerful enough to allow the TAP to reveal everything (I am assuming the source is reasonably good).

Really glad to hear the news that the tap will be flowing again. John has come up with a product that is excellent and I certainly hope that more will be able to enjoy his products again!
This weekend I tried another audition of a very highly regarded tube linestage, retails for $6500.00, to compare to the Bent Audio Tap. Everyone always talks about the "magic" of great tube linestages regarding harmonics, image density, and that " more natural midrange" were most of the music is contained in.

Well, after about six hours of listening, I wanted to put my Tap back in for the following reasons:

1) After over four years of using the Placette Active buffered stage and now the Tap, both are passives, I guess I'm addicted to pure and pristine transparency, total clarity, and just an "easyness" to the flow of the music that either SS or Tube linestages do not offer, at least in my system.

2) The tube linestage offered a very good large soundstage, but was far beyond the Tap regarding "air" between the Players and the individual players did not sound as real as they do on the Tap.

3) Yup, I heard that "magical midrange" on the tube linestage, but the addition of a slight warmth/lushness did not bring me closer to the emotion of the music, but kinda got in the way because it sounded to my ears as an additional coloration not part of the natural timbres of the music.

4) Who ever says that passives just can't do dynamics or give the body to the music that actives can, should just come over and listen to my system. The highly regarded SS linstage was better in this regard then this weekends Tube linestage but both were not as good in the lower end then the Tap and the Tube linestage's PRAT compared to the Tap was missing in action.

It always comes down to personnal taste and system synergy, my hunch is that with my Pass XA-100's adding warmth/musicality this tube linestage addition of a slight touch of "lushness/warmth/romance" took my system to far towards thick "velvet" and was not a good match in my system. If someone had SS amps or speakers that would lean towards bright or forward sonics, I understand way a tube linestage would be just the ticket to give some warmth to their overall system sonics.
Teajay, so to complete the recent audition notes, can you reveal the name of the highly regarded tube line stage?
Audphile1, the tube linestage was the Joule Electra 150 MK11. So far I have done home auditions with Audio Research(not the Ref3, but the model before), Hovland, Shindo Labs, Wytech, and Lamm, and still like the Tap better in my system.
Teajay, thanks.
TAP seems to be working magically in your system within the current config. If nothing beats it, why bother?
Enjoy!
"2) The tube linestage offered a very good large soundstage, but was far beyond the Tap regarding "air" between the Players and the individual players did not sound as real as they do on the Tap."

Perhaps I'm reading it incorrectly, but are you saying the Joule was better than the Tap as it relates to air between the individual players?

I used to own an LA-100MkIII and have been considering an LA-150 MkII as an alternative to compare to my passive S&B TVC. For the money, especially at used prices, Joule preamps are some of the best out there so any clarification would be appreciated.
Clio09, your quite right my description does not make sense, so here's the clarification.

The tap offered much more air around individual players and each player sounded more three dimensional then what the Joule 150MK11 offered in its soundstage.

Hope this helps, sorry for the confusion.
Thanks for the clarification. I notice similar attributes of my TVC as you have with your TAP. I am awaiting John's decision on what transformers he will be using in the future, but overall I have been very happy with the S&Bs.
This thread is a bit old and the Bent TAp with autoformer has been released. I did not own the previous version with the S&B trannies, but I did own a highly regarded S&B passive by K&K. I don't know if the difference is due to the difference in manufacturer, but I find the autoformer version of the TAP clearly superior to the S&B passive I previously owned. No leaness I can detect running my Music Reference RM9SE and incredible presentation of intonation by which I mena tracking changing levels of volume and and pitch which to me is critical to getting the musical message; that it the new Bent Tap is very musically articulate. No loss of dynamics that I can detect compared with some highly regarded tube actives I have own. With the right matching amp and source voltage, this passive is about as good as it get I think - worth an audition, especially if you own a tube amp with a 100kohm or higher input impedance and sensitivity half the output voltage of your source.
Hi TeaJay - great review. You nailed so many aspects of the Bent Audio TAP. I've had the TAP Silver (Silver transofrmers and wire) balanced version in my system now for about two months and it has been incredible. I also own two wonderful tube preamps and I love them both; The MFA MC Reference (a prototype built for CES), and a Messenger preamp. The TAP looks elegant but rather 'umble next to these two, but is very modern looking I think. I was surprised when I got it. Being used to big preamps it was a bit of a shock at how much smaller the Bent TAP Silver is than the usual overdone two-box affair. But small in performance it is not. The TAP is without any doubt the most transparent preamp I've ever heard - then again I've not heard the Placette Active Linestage. As you well describe, one of the most engaging aspects of the TAP's transparency is the sense of openness, freedom, and air - air - and more air. I love that feeling, which is total magic with certain CDs and types of music. The TAP does not lack for any weight or substance, it demolishes many preamps I've owned and heard in this respect. I find that the TAP allows music to flow unimpeded - 'musical-flow' is in a different class to most other preamps also. There is a real integrity to what one is hearing. Images are fully formed - the mind is not racing to put things together. I don't find it to be sensitive to cable length either, and this is something I was a little concerned about before I got it.

In all, your review of the TAP was great.
Oshag, how does the TAP directly compare to the Messenger?

Are there significant differences in their musical presentation?
Telstar and Pubul, Dave Slagle of Intact Audio supplies autoformers for Bent Audio.
Both Bent and Intact offer a simple autoformer double mono preamp that use the same autoformers.
Bent's upscale product, the Bent X preamp, has 61 one db steps, remote volume control, source switching and a defeatable active line stage. It is a more versatile product.
The core technology is the same for both companies, Slagle's autoformers.
So, your choice should be based on features, convenience and your ability do do it yourself, because AFAIK Slagle does not supply finished preamps.

There may be slight differences if you DIY and choose different RCA female connectors or different internal wiring, that's all.
I have built several TVCs using Dave's autoformers and IMO they are superior to regular transformer volume controls, specially in bass control and dynamic punch.
Casouza, were your "regular" TVCs using the S&Bs? I own the Bent Tap-X, and once owned a TVC with S&B 102 MKIIIs. I just never had the opprotunity to A/B, but most comments I have heard, seem to prefer the autoformers in terms of sound.
Dgarretson, please explain impedance matching. What values should I look for in my choice of amp with Bent TAP X?
Hello JB, I think a ratio of source ouput impedance to amp input impedance of at least 1:10 is generally necessary. You couldn't go wrong with a tube amp of typical input impedance >100K.