Jeff Rowlands Amp and Dac vs. VAC amp and DAC


Hello, I am new to this forum but I have a question. I am trying to pair an amp + DAC with my Wilson Sabrinas. I have listened to Jeff Rowlands integrated with the Aeris DAC. And the VAC Sigma integrated with the Aeris DAC. Price is a factor and so is space. Does the 625 need a pre-amp? Any suggestions or thoughts? 
rinpoche
The TV and film aspect of the system is one of my concerns about choosing tubes over SS. I don't really have enough room for two sets of speakers and another receiver. We could just use the TV alone for sound on a day-to-day basis and use the 'complete system' for films and perhaps our favourite shows. The Jeff Rowland 625 S2 won't be an issue, but the VAC, I think, will. We do watch a fair bit of TV because I am working on a book on film at the moment, but again I don't need to have it through the main system all the time. My main interest and purpose here is music, and secondarily to have access to TV and film when desired. I think it would mean going through tubes more often, is that right? Sort of like servicing a car if you drive it more? Or are there other issues I don't know about? Is the VAC delicate? Can it take more hours of useage? Or is it just going through the tubes faster and having to replace them? 

Yes, the advice here has been fabulous. Thank you all so much.
Hi rinpoche,
It seems like the Rowland amplifier really impressed you but nonetheless you appear to be more captivated by the VAC.  Of course the more often you use the VAC  the sooner you'll have to replace the tubes.  Good news is that the amplifier doesn't require a multitude of tubes and the KT  88 output tubes are modestly priced (compared to my amplifier's 300b tubes).  The VAC is "very" rugged,well built and reliable.  A good friend of mine had the VAC Phi 300.1 and had no problems with it at all during his 5 years of ownership. As has been acknowledged,  you need to hear both amplifiers in your system. 
Charles, 
Hello again to all of you. I wonder, could I hook the Jeff Rowlands Aeris DAC to a VAC Phi 200 amp directly? Do I need an integrated amp or a pre-amp? Doesn't the Aeris act as a pre-amp, at least for now? I mean, what do you think?  
Hello again to all of you. I wonder, could I hook the Jeff Rowlands Aeris DAC to a VAC Phi 200 amp directly? Do I need an integrated amp or a pre-amp? Doesn't the Aeris act as a pre-amp, at least for now? I mean, what do you think?  

With the new VAC 170IQ and 200IQ, I would avoid Phi 200 unless it's a GREAT GREAT deal.   Used prices will drop with demand for the new amps increases.

If buy Phi 200 used, it would be difficult comparing Aeris with and without a preamp so try comparing Aeris to a 200IQ.    Once you have a barometer on the different combinations, then go shopping for Phi 200 if chooses. 




Rinpoche,
If your question is technical(based on specifications), I submit Almarg would be best to answer. The Aeris DAC does have a volume control, but I think it sounds better with a preamp. You need to take what I'm saying with a grain of salt, because I'm firmly in the camp of those that believe most systems sound better with a very good preamp in it.
Thank you. This is helpful. I wonder if you could elaborate as to what exactly the new VAC 170IQ and 200IQ are? I don't see them on the VAC website. Am I missing something? 
Rinpoche, the 200iq and the 170 (which incorporates "iq" functionality but omits those letters from the model name) are linked to on this page.

Ricred, thank you. In this case I don’t see any technical issues that would arise in using the Aeris DAC directly into a VAC or Rowland power amp, or into most other power amps for that matter. However both Ricred and a member who reviewed the Aeris in this thread that I referenced in one of my earlier posts have stated that they found adding a preamp to be sonically beneficial.

In the recent past there have also been lengthy discussions of this question pertaining to DACs in general, in situations where the DAC provides a volume control. See this thread, for example. My perception has been that the prevailing (although certainly not unanimous) consensus has been that inserting a high quality preamp into the chain is likely to be sonically beneficial in most cases.

FWIW, my own instinct would be to follow Knghifi’s recommendation and go with one of the new "iq" power amp models, initially without a preamp, ***PROVIDED*** that confidence can be established (preferably by audition) with respect to the issues I raised regarding the sonic synergy or lack thereof between a VAC tube amp and your Sabrina speakers. (And btw, the inclusion of a 1 to 2 ohm output tap on these models, that is not provided on the Sigma integrated, could very conceivably be beneficial in that regard). At a time of your choosing, now or in the future, you could then assess whether the addition of a preamp would be worth its cost to you. Perhaps by buying one used and then selling it if it did not provide a worthwhile benefit.

Finally, I’ll second the comment Charles provided earlier to the effect that VAC equipment is designed in an extremely robust manner, and can be expected to be very reliable. And their support and customer service is second to none.

Best regards,
-- Al

Rinpoche, 170IQ and 200IQ are VAC latest amps.  From what I was told, 1st lot of 200IQ has already been sold.  All I'm saying is used prices for Phi200 will drop so keep in mind when negotiating.

Kevin Hayes introduces 170IQ and 200IQ at CES

200IQ in action at CES

Wilson Sabrina with VTL at CES

I don't have 170IQ retail price but 2 170IQ is another option.
A lot will depend on how much money  one wants to spend. A used VAC Phi 200 is a wonderful amplifier and much less costly than the newer VAC IQ  amplifiers. It would be ideal to compare the Phi with the newer IQ amplifiers. The Phi could be as good sounding or verify close,who knows without listening?  Given the cost of these amplifiers traveling to actually hear  them would be helpful. 
Charles, 
From all the indications, real time bias dramatically improves SQ.  The owner running 200IQ in mono configurations had Phi 200s.  Bottom line is how much do you want to spend?
Exactly, how much to spend? Listening is inherently subjective,  jaw dropping experience for one is modest or subtle difference for another. 
Charles, 

Thank you all again. I will try to listen to the IQ gear this weekend and see how it compares both in price and sound with the Sigma and the Rowland. I am booked to listen on Saturday morning. Not with the Wilson's but with speakers at the shop. I will take Al's advice to heart and all of your inputs when listening. There is a lot to digest here and it has been amazingly useful. Instructive. Thoughtful. And informative. I can't thank you all enough for your time and wisdom. Will let you know how it goes if you are interested!!!!
Rinpoche,
I look forward to your amplifier  listening  impressions. It's clear to me that you have good ears and can choose what type of sound presentation you prefer. I am very glad you have this opportunity to hear these amplifier candidates. It should be much fun as well as informative.
Charles,
Thank you all again. I will try to listen to the IQ gear this weekend and see how it compares both in price and sound with the Sigma and the Rowland. I am booked to listen on Saturday morning. Not with the Wilson's but with speakers at the shop. I will take Al's advice to heart and all of your inputs when listening. There is a lot to digest here and it has been amazingly useful. Instructive. Thoughtful. And informative. I can't thank you all enough for your time and wisdom. Will let you know how it goes if you are interested!!!!

You can also try IQ with and without preamp from Aeris.
Not with the Wilson's but with speakers at the shop.


Rin, I would expect the speakers you hear at the shop would be well matched to the VAC amp but in any case it may be hard to predict the sound with the Wilson's without hearing the amp and speakers together especially in that the Wilson's may not be particularly tube amp friendly.

Do you know what speakers specifically you will hear at the shop?

You know, that is a great question: what speakers I will listening to at the shop. The shop insists a 3-way is a 3-way. I feel a bit pushed on this one, but there are so few high-end shops in my neighbourhood. They used big Focal speakers that cost $10,000 more than the Sabrinas. So, I agree it is not a fair audition. I am trying, though, to hear the differences in the amps -- but are you saying the JR gear is more suited to the Sabrinas. The Wilson people I spoke to at Wilson Audio love VTL, VAC, ARC, and Nagra tubes with the Sabrinas. They said they pair well, in their opinion. I asked for a home audition but I don't see that happening. Is it the norm for shops to do that? 
The shop insists a 3-way is a 3-way.
Speaking frankly, this comment by the shop is nonsense.  Some 3-ways (and other kinds of speakers) are best suited to be driven by solid state amplification, some are best suited to be driven by tube amplification, and some are equally at home with either.  A speaker having a nominal impedance of 8 ohms or more, and having impedance that does not vary greatly as a function of frequency, and having higher than average sensitivity, will usually be suitable for use with either.  To the extent that those criteria are not met, things become questionable.

Over the years many of the models Wilson has produced have been used successfully with both kinds of amplification, even though many of those models have had 4 ohm nominal impedances (like the Sabrina).  However, the graph of impedance vs. frequency for the Sabrina that I linked to in my first post in this thread, coupled with the associated comments that I quoted, as well as a comment in the main body of the review, as well as the Sabrina's somewhat low sensitivity, raised caution flags in my mind as to the suitability of that model for use with tube amplification.

However this comment:
... The Wilson people I spoke to at Wilson Audio love VTL, VAC, ARC, and Nagra tubes with the Sabrinas.
... as well as the comment you indicated earlier that Kevin Hayes had provided, as well as the video Knghifi linked to showing the Sabrina being driven by a VTL tube amp, as well as the inclusion of a 1 to 2 ohm output tap on the VAC iQ models, do provide a fair amount of confidence, albeit obviously not as much as an audition with your speakers would provide.

Best of luck as you proceed.  Regards,
-- Al
 

Any of you guys using a VAC, VTL or JR set up with THIEL loudspeakers? Cabling?
No Thiels in this set up. For now larger Focal, VAC, JR and I believe Transparent cables. 

Again as I mentioned before, I heard the Sabrina's with the wonderful ARC GSi75 tube integrated. It was just amazing. That integrated had an iron fist on the speakers and am still thinking about it since I heard the setup six-eight months ago. I've also heard the Sabrina's with the new D'Agostino solid state gear and it was also a great match. But I think the point at least several others are trying to make is, you, Rinpoche need to hear the Sabrina's with the amplification you are considering purchasing. Als comments are a good start, but the end of the story is whether you like the sound or not. It makes no difference if an amp can drive a speaker if you don't appreciate the sound they make together.

The comment made by the dealer that a "three way is a three way" is unfounded. For so many reasons included all that were named by Al. Many amps will drive many speakers but if they don't have the magic you are looking for you'll just be disappointed. Make sure, to the best of your ability, that you audition the specific components together you are considering purchasing so that you will know whether or not you are getting what you'd hoped for.

Finally, I heard my exact system in the store I bought from. When I got it home, well, lets just say I had a long way to go to get it most of the way there to how it sounded at the dealer. My room is not as big and most likely the power they had was better too. It is a big crap shoot but at least if  you hear the components you want to run together in the same store at the same time you can attempt to make the best decision you can.

I do wish you the very best in your journey and that you end up with what  your really desire to hear - music!

Pokey77,
The fact that you felt that the ARC 75 watt integrated amplifier mated so well with the Wilson Sabrina is encouraging for very possible success with the VAC. I'll say it again that for the cost of the considered amplifiers an in home audition should be available. This is not a trivial purchase. Rinpoche we're pulling for you. 
Charles, 
You are all so sweet. Thanks for pulling for me. I will insist on a home audition -- I totally agree this is only fair especially at these prices. They said I should bring the speakers to them. To be honest, I was flabergasted. I mean they are not easy to transport -- the amps are so much easier.

I will let you all know how it goes and yes please keep rooting for me. It really helps. You have all really helped. In fact, you have already changed my mind to hear the 170 or 200 IQ. So, I am taking your advice and checking into it thoroughly. 
Rin,

I use a single VAC Phi 200 to drive some TAD CR-1's that are a challenging load, and they handle it well - - been enjoying this match for 18 months now.  The VAC has drive and pretty good bass grip for a tube amp IME (easily better than the EAR 890 I was using before with 8 KT-90's).  Looking at the impedance and phase curves of the Sabrina, I'm thinking the Phi 200 would drive them well, too (using the 1-2 ohm tap, like I do for my TAD's).

Regarding tube upkeep, I did have a couple of the Shuguang KT-88 tubes die on me prematurely, where it seemed that their internal structure fatigued apart due to the on/off thermal expansion.  No drama or troubles other than having to get a replacement.  This happened in my first of four years of use.  I moved to Gold Lion KT-88's matched beautifully by TC Tubes and have had just solid performance, no troubles, and slightly better overall sound for my system (a bit richer in tone, while still being extended - - TAD's like that).  Setting the bias on the tubes is really simple with the VAC system, takes only 60 - 90 seconds, and I have experienced virtually no drift over time.

I listened to a lot of SS amps, but I keep coming back to tube amps because of that same magic that you are hearing!  I'd easily go with the VAC, but you certainly should hear them in your system and home first.  Any dealer selling equipment of this cost level should get behind a home audition, IMO.
Good news. The stereo store owner has offered to do a home audition once I confirm the amp (or two) that I have narrowed it down to. That is a relief. And, they are getting in the 200IQ in a week so I can also hear that. All is moving along and all of you who contributed to this thread played a major part. As I say each time — THANK YOU. Whatever experience or advice you have to share is really welcomed and is being digested and used in both my negotiations with the store and my own listening education. Hey, should we start talking about great songs to use for an audition!!!!!! LOL
Well I'm glad that the store owner is behaving reasonably,  the audition of the amplifiers with your speakers is ideal. Now all you have to do is listen and trust your ears. 
Charles, 

I'd be very interested to hear your comments after auditioning the iQ version of the VAC, so please post your experiences.  I'd love to get a good audition of one.
I will. It doesn't arrive in the shop for another week, but I will definitely let you (all) know. R
I spent the afternoon at Fidelis looking into analog and they are dealers for Wilson and recently VAC.   They have Wilson Sabrina, VAC 200iq and VAC Sigma 160i SE in stock.   200iq and Sigma 160i SE in different rooms so I just demo 200iq with Sabrina.   Preamp was VAC SigMKIIa SE (my current preamp) and not familiar with the DAC ... something expensive. 

Overall I found the sound very good but boomy bass.  It seems the amp cannot control the bass, impedance curve or needing setup fine tuning. We switched 200iq with D’Agostino Momentum Stereo Amplifier and WOW!   No more boomy bass, actually less bright, more transparent, doesn't sound like tube or SS but just music.   I know I know not a fair comparison, $14K vs $35K.    This is the 1st time I heard VAC SigMKIIa SE with Momentum and it's an EXCELLENT match.   Now getting dangerous thoughts in my head ... Hmm!

So if you are buying from a dealer, insist on home demo before writing a check.   If you are set on Sabrina, Rowland might be a better option so don't rule them out.    Dealer can help with Sabrina setup.  Another option is go with tube pre and SS amp.    
Knghifi,
See her post above, she's doing a home audition with both the Rowland and the VAC driving her Sabrinas. 
Charles, 
Knghifi, thanks for that input.  Do you happen to know which output tap they were using on the 200iq?

Regards,
-- Al
 
It is possible for me to audition the Momentum with the Wilson's. The Wilson dealer also sells D'Agostino. But the price is crazy for me! I am barely scraping to afford the VAC and the JR is even a bit more. I have no doubt it is stunning in many ways!! Thank you for you suggestion. I will also seriously consider the JR. It is also beautiful in its weight and clarity. I started the thread because it is a hard decision and both amps have their benefits. Will let you know.
If the D'Agostino amplifier exceeds your budget I wouldn't even think about it.  This is where High End audio gets people frustrated and in trouble with spending.  You'll find a terrific amplifier within your price range to match your Sabrinas,  very possibly today 😊
Charles, 
Sounds like fun and done the right way.   Sure to be a winner in the end. 🏆

Charles, that was exactly the point I was trying to make about the ARC tube integrated; it makes sense that other tube product should also be able to synergize with the Sabrina's as well. And Knghifi, just as a data point, the presentation with the ARC GSi75 did not display bloated bass. Maybe setup in the room needed tweaking? When I heard the Sabrina's with D'Agostino Momentum Amp and Preamp, that was very sweet too. I could have been very happy with that setup, but it is well outside my budget. Again, still fun to dream. I hope that while I'm at THE Show in Newport in a couple weeks that I can hear the Sabrina's with some other amps/preamps that also synergize.

Rinpoche, great to hear the dealer will bring over equipment for you to audition; at this price range that is expected really. I hope that includes the DAC or DAC(s) that you plan to drive the amps with too. Then you'll know exactly what you will have when the check is written or the credit card is read! Hope you are having fun. And take Charles' advice, if the D'Agostino gear is not in your comfort zone that's OK, there'll be something that is and you'll be very happy as well.

Well rinpoche curious and very interested folks here want to know what you heard.  I hope it was a fun and insightful audition today 😊
Charles, 
Well, in many ways the audition was great BUT both amps have their plusses and minuses. For example, the JR is deep and rich. It has a control quality that seems to excel in the midrange which, in my opinion, is gorgeous. Remember, I don't know the technical terms for these things but it is what I heard. I would say it is a mature amp. One that you could live with for a long time. Was it analytical? Maybe. And this is where the VAC Sigma comes in. Not as much punch (weight?), clarity or sound distinction, but an overall presence that is engaging. For acoustic vocals the JR wins hands down in my view. For chorus pieces maybe the VAC. For quartets, opera and classical they seem even in some ways. I missed the JR when the VAC was on, and the VAC when the JR was on. Perhaps when I go to hear the IQ both of these differences will be captured. Or, as some of you have suggested, a tube pre-amp down the road with the JR. Does that sum it up? 
Yes your summary is fine and there are no problems with your descriptive writing skills, I understand you clearly . Tube preamp with the Rowland could certainly be a very good option. One thing to keep in mind,  you can modify the sound of a tube power amplifier via trying different brands of tubes  (both the output and the input /driver tubes). This is what many refer to as "tube rolling". You can tailor the sound of a tube amplifier. 

One thing I can tell, you know what you're hearing and that's an excellent trait to have. I have all the confidence that you'll choose wisely,  you know what you like. 
Charles, 
rinpoche ,friendly reminder, be sure you are using the appropriate speaker tap (ohms) with your speakers. 
Charles, 
I missed the JR when the VAC was on, and the VAC when the JR was on. Perhaps when I go to hear the IQ both of these differences will be captured.
Given the Sabrina’s impedance curve that I linked to earlier, as well as the listening experiences with the Sabrina that have been described by some of the others, I suspect that the 1 to 2 ohm output tap of the 200iq stands a significantly better chance of accomplishing that than the 2 to 4 ohm tap, and certainly than the 4 to 8 ohm tap.

I presume, btw, that what you listened to today was the Sigma integrated (which does not have a 1 to 2 ohm tap), and that its 4 ohm tap was what was used.

Continued best of luck, and best regards,
-- Al


rinpoche,
My current amp is the JR 625 S2. I always like to preface my comments with, no absolutes in audio and one man's medicine is another's poison. To my ears the 625 S2 is simply outstanding. The midrange is produced with a realism that is hard to describe, it's truly a chameleon that's capable of reproducing whatever is on the recording...e.g if the soundstage is wide or if there is no bass in a recording that is what you will hear. The only thing that I would want more of is power because of my room's dimensions and the size of my speakers. If I had the money I would move up the JR line. 
The only thing that I would want more of is power because of my room's dimensions and the size of my speakers.
Rick, the Monitor Audio PL-500, at least in version ii, has a rated maximum power handling capability of 400 watts, and a nominal impedance of 4 ohms.  Your Rowland 625 S2 amplifier can deliver 600 watts into 4 ohms.

Best regards,
-- Al
 
Al,
Yes, you are correct. I find that more power usually provides a sense of ease to the music. I can't say the JR 725's is significantly better, because I've never had it in my system. I would like to compare the two. I'm very, very happy with my system, but love to talk about audio and the possibilities. 

I wonder if you could expand on what you mean by 'ohm tap' and which amp would be best in that regard with the Sabrinas?

The JR will probably provide the power the Sabrinas need, but will the VAC Sigma and the 200 IQ? I felt the VAC was a bit bright (?) at times with these larger Focal speakers. But I still have yet to hear them amps with my own speakers. Once we narrow it down, I trust that will happen.
I wonder if you could expand on what you mean by ’ohm tap’ and which amp would be best in that regard with the Sabrinas?
Rinpoche, most tube amps drive their outputs via a transformer, which converts the high voltage/low current signal that is processed by the tubes to a lower voltage/higher current signal that is needed to drive a speaker. Usually at least two transformation ratios are provided (i.e., how much the voltage is stepped down and how much the current is stepped up), including one that is theoretically best suited for 4 ohm speakers and one that is theoretically best suited for 8 ohm speakers. Those are provided on different terminals on the rear of the amp, and are referred to as "taps" because the terminals are connected internally to different points on the output "winding" of the transformer.

The 200iq provides a third tap, theoretically best suited for speakers having even lower impedances.

The circuitry in nearly all solid state amps operates at lower voltages and higher currents than the circuitry in nearly all tube amps, so most solid state amps do not need or have output transformers, or multiple output taps.

If you click on the photo of the rear of the 200iq, shown on this page, you will see that their are a total of 8 binding posts/terminals, 4 for each channel. For each channel, one wire from the speaker (usually the black or negative one) connects to the "Com" terminal, and the other wire from the speaker (usually the red or positive one) connects to one of the other 3 terminals, corresponding to the chosen tap.

Since most speakers have impedances that vary significantly over the frequency range, a nominally 4 ohm speaker will not always sound best when connected to an amp’s 4 ohm tap, and an 8 ohm speaker will not always sound best when connected to an amp’s 8 ohm tap. It is often best to try each of the taps that are provided.

The impedance curves I have seen for several Focal speakers all show a substantial rise in impedance occurring in the upper mid-range and/or the treble regions. Throughout most of the spectrum your Sabrinas also have an impedance that rises considerably as frequency increases. The interaction of relatively high amplifier output impedance with those kinds of speaker impedance characteristics will result in a brighter sound than if the amplifier has a lower output impedance, everything else being equal. Output taps on a tube amp that are intended to drive lower impedances (e.g., 4 ohms) have lower output impedance than output taps intended to drive higher impedances (e.g., 8 ohms). Solid state amps almost always have effective output impedances that are near zero.

So that probably explains why you perceived some brightness with the VAC/Focal combination, and I suspect explains why Knghifi perceived some brightness with the combination of the 200iq and the Sabrina (especially if the 1 to 2 ohm tap was not the one that was being used). The brightness was not the result of the amp’s intrinsic sonic characteristics, but rather was the result of a non-optimal impedance match to the speaker, which would be minimized (although perhaps not entirely eliminated) by using the 1 to 2 ohm tap that is provided on the 200iq.

As far as power is concerned, considering the sensitivity of the Sabrina and the power capabilities of the VAC amps, as I mentioned early in the thread I suspect that if you were to have a problem it would only be on recordings having particularly wide dynamic range (i.e., particularly great DIFFERENCES between the volumes of the loudest notes and the softest notes). Some well engineered minimally compressed classical symphonic recordings come to mind, such as many of the Telarc orchestral recordings from the 1980’s that were notorious for having very high volume bass drum beats. On most recordings, and **perhaps** even on those, I don’t think you would have a problem, though. This assumes that your listening distance, room size, and volume preferences are not significantly greater than usual.

Best regards,
-- Al

Wow, that was amazing. And in some broad sense I think I understand. Not the technical specificities, but the general theory you explained. I will remember that when I go to hear the 200 iq. I am a bit obsessed now, wanting it to be done — and just to be home listening, but it is a process and the results will be something I live with for a while to come, so patience here is a virtue. Thank you all, especially Al, for explaining and walking me through the intricacies of this exciting adventure. I hear you — LOL, no pun intended. 
rinpoche I would say Al's technical wizardry and completely correct explanation notwithstanding try each output tap until you find the one that sounds best to you. It's likely to be the one Al suggests but it may not be, we all have different ears. Have fun!
Hi everyone.
Never heard Wilsons though heard a lot of them.
Would LAMM pre/power plus some DAC beat both Rowland and VAC overall? LAMM hybrid power, I mean. What if it could?
Inna,
It's strictly subjective as to what combination of components someone would prefer to drive these or any  speakers. For instance I had a friend's Lamm push-pull tube amplifier in my system and I didn't care for it, my friend agreed. That's just us,  another listener could have the opposite impression or be somewhere in the middle. 

Best case scenario is that you must actually do some listening with audio components to come to a definitive conclusion.  Rinpoche is taking the right approach. 2nd factor is confidence in yourself and trusting what you hear. 
Charles, 
It’s strictly subjective as to what combination of components someone would prefer to drive these or any speakers.

Yes preference is 100% subjective.

But performance is not and can be measured.

Performance is key to the best sound possible IMHO though any sound might be preferred still.

Limitations with performance may take longer to discover as amp is asked to work harder over a period of time. Like putting a very good quality but  undersized engine in a performance vehicle.

Best sound over time usually occurs when components are not required to run harder than designed to and able to deliver the music with ease.