What Power Amplifier Should I Buy?

Still think, despite your devotion to them, the Revel's are your issue. Please don't shoot the messenger. Why not try something else? Vandersteen, Tannoy or Focal to name a few.

pick up a PARASOUND JC5, fantastic match with REVEL.  gobs of power, images fantastically.  and slightly used can be had for $4500-5000

@kevemaher . I would buy a 2nd 2.5B and use them as a Monoblock for each channel. 

My rec is to save some money by getting an old-stock Parasound A21. Parasound currently has some available direct from their factory store for a great price:

https://parasound.com/products/vintage-a21?variant=49660977873215

I’ve owned a good number of power amps <$5K and the A21 is as good as any of them and better than most. Its distortion profile is 2nd-order dominant and it’s considerably quieter than the newer A21+ (and sounds better too). Once the A21 warms up for a couple hours it just sings. I prefer it to the $6K Coda No.8.

I previously owned some F208s. The A21 amp paired with a low-distortion, low-noise preamp (Benchmark LA4, Bel Canto Pre5 for examples) makes for excellent synergy with the Revels.

Once the A21 warms up for a couple hours it just sings. I prefer it to the $6K Coda No.8.

I never heard the A21, but I was very impressed with the A21+. For the cost it was an excellent amp. I sold that to get the CODA #8 and thought it was more detailed and as powerful as the A21+. I now have the CODA #16 which is better than the #8. The Benchmark LA4 with the Parsound is a great combo. The Holo Serene preamp is another similar option.

Using a stereo amp as monos is not a good idea. Better to get dedicated monos. I would get the stereo 4B3 over 2 2.5’s. A lot of technical explanations on Audiogon about why this is the case.

I am selling my Sanders Magtech amp (500 W) which I think is as good and maybe preferred over the 4B3. Definitely great on Maggies but I am not sure about the Revel and Sanders synergy. My Sanders was not as good as I expected on my Yamaha NS5000 but on my Magnepan LRS+ it was amazing.

The 4B3 should be good on Revel. I used to have the 4B-SST and then the 7B-SST on Revel Salon 1. It was not perfect but not too bad. The extra power of the 7B-SST was noticeable on the Salon 1. Such killer bass on that speaker.

Orchard Audio Starkrimson Ultra DMC 2.5 is what you want. 

Agree with YYZ I would not use the 2.5s in mono, but as I recommended in my post if you use them to vertically biamp your speakers (since they are biwirable) there are many advantages to that over a larger stereo amp.  

Get a second HSU sub no matter what. Get one before making an amp change because two-four subs is where you want to be.

I`ve heard the Revel 208`s many times used with 3 HSU subs.

Running the subs up to 120 Hz is only going to muffle/muddy the bass up.

Use 60-70 Hz and play with Q settings and volume level.

i have just the amp for you in your price range, recently retooled by jeff at conrad johnson, i dont play it anymore because i sold the preamp.  look under audiomart under conrad johnson, but its a mccormack dna 500...... 500w the 2nd best amp ever made.

Buckeye Purifi. Objectively one of the best amps on the market, and without the snake oil markup.

StringAmp d220 power amp ( same designer as for the Gamut d200 versions)

Michael has perfected the design all these years and his amps are built to last a very long time. He told me that the amps are even better sounding now, a lot of great reviews on the old Gamut amps on the net for people to investigate.

Hope to get one myself one day.

 

 

I never heard the A21, but I was very impressed with the A21+. For the cost it was an excellent amp. I sold that to get the CODA #8 and thought it was more detailed and as powerful as the A21+. I now have the CODA #16 which is better than the #8. The Benchmark LA4 with the Parsound is a great combo. The Holo Serene preamp is another similar option.

The A21+ was disappointing for me. It produced plenty of grunt but otherwise I found it inferior to a 20-year-old OG A21 I had at the time. The A21 was/is considerably quieter and cleaner sounding. I suspect that’s the real reason for why the 21+ is not THX certified despite its claimed specs. The original 21 was measured by Miller Audio Research lab back in 2011. Other than maximum unclipped power, it posted better numbers than the 21+ did in Stereophile’s measurements. 
 

I agree the Coda No.8 is more detailed—it has a lower noise floor than most amplifiers I’ve tried, which probably contributes to that detail. By comparison, the A21 is a little rolled off in the top octave, but on balance, I ultimately preferred the A21 for the way it “effortlessly” went about controlling the speakers, which I didn’t quite get from the No.8. I consider the two amplifiers roughly equal in subjective performance, but the No.8 sells for over 2X the money on the secondhand market, so in that sense I consider the 21 the better value, especially for tougher speaker loads. The difference in outright power between the 21 and No.8 becomes much more apparent on speakers like Magnepans. 
 

The potential downside of the A21 is that its inherently laidback character makes compulsory the use of transparent upstream components, like the Holo Serene you mentioned. That is, if the system’s speakers are voiced neutral or warm. 

@kevemaher 

One likelihood (based on my experience with F208s) is that your current amplification already outclasses your Revels. In other words, the speakers are likely a bigger bottleneck in the grand scheme. The 208s are nice speakers at their price point, but you’d likely get more “bang for your buck” by saving money toward a pair of pre-owned Salon 2s or others of similar clout.

IME, even a mid-tier integrated amp can scale up surprisingly well with >/=$10K speakers. I realized regrettably late in this game that loudspeakers are the major bottleneck in probably 90% of audiophile systems, even when a relatively humble amplifier is employed. For example, I am quite certain I’d rather be stuck on the proverbial “desert island” with my Børresen X3s and Yamaha integrated than with Revel 208s and cost-no-object separates. 
 

…just something to consider 🫣
 

I have three ideas for you but one was already mentioned. Adding a second complimentary subwoofer would help. It's adding more watts, more sound and also taking some load off your main amp (which you like). When I did this, it really opened up the overall soundstage and I felt more amp was producing more realistic organic sound. The second idea I offer is to do the first thing (add second subwoofer that is the same model) and add mono amps of the kind you have. Bryston makes good amps, and if they offer mono amps, I think that would keep that good sound you stated you like. Third idea is to change speakers. I know this maybe a less popular idea, but the facts are some speakers are MUCH easier to drive than others and still sound great. I have had my share of speakers and that is simply an easy solution. Good luck.

Two things come to mind.  The vintage pre-amp may not be up to the task. Ensure that you choose a preamplifier with 2 outputs.  Ultimately consider bi-amping, running the Bryston's on the low-end and something else on the tweeters.  Could be another stereo amp or monoblocs?  You have options with the Bryston's like "jimmy2615" stated.

@jimmy2615   @perazzi28 

I've talked to Bryston about bi-amping. They recomment against doing it because the speakers drop below 4 ohms at the xover to the highs (2.2 KHz), although they hedged saying I moght be OK because there's not much power/current needed at that frequency.

I'm not taking that chance.

Biamping will give me more power only if I use two outputs from the preamp. Not very many preamps have two (balanced) outputs. The ML 38s doesn't. But the Bryston BP-17 cubed does!

What's the word on this preamp? I've looked at it before thinking I would try it or the Benchmark LA-4. I wound up getting a Cary tube power amp. That didn't change the sound very much, so I went back to the Bryston amp.

@scm I deliberately crossover at 100-120Hz because of a nasty room resonance at 40Hz. This creates a big dip at 80Hz that can't be EQed away very effectively. This dip is very strong with the f208 speakers. It is much smaller with the sub. I've placed the XO frequency a reasonable distance from that resonance. I've used REW and other tools to guide me.

I've listened to sub only at 75, 100, and 120 Hz. I cannot hear voices at all. Frequencies below 200 Hz are radiated into a half sphere, with no dependence on angle. How can this muddy the sound?

Of course, I could be wrong. Could you explain how this higher XO frequency creates muddiness? Thanks.

Two subs may be the way to go.

@kevemaher thats why I recommend not using them as monoblocks, which is what Bryston is talking about. In this case they are bridged and each amp becomes one channel and doubles the power into 8 ohms. Try to find specs though on what they put into 4 ohms when bridged. It’s not recommended for speakers like Revels.
If you use one channel though from each amp to power the highs and lows of a speaker you let the amplifier ‘see’ a much easier load than if it was powering the whole speaker, and offering much more headroom. Active speakers (like ATC) have an amplifier for each driver in the speaker. You’re right, and as I mentioned in my first post you need a preamp with two sets of outputs or you can get a y-splitter for your preamp. Incidentally, when I had two 2.5s I tried them in this configuration as well as bridged monoblocks, powering the Revel 228 Be. It sounded ok as monos but not as good as the other way. A bit muddy. And two amps definitely sounded better than one, but the difference was not huge.

I don’t think you could go wrong with a 3B or a 4B, but I was looking at it from a price perspective. Probably cheaper to pick up a used 2.5. But also, from a power perspective, 2 smaller amps may be better than one larger. The 2.5 is conservatively spec’d. It’s basically a 150/300 w amp into 8/4 ohms. So biamping, at 4 ohms you’re getting 300 w/ch into the mid and tweeter, and 300 into the woofers, and each amp channel sees an easier impedance load. With something like a 4B you would get 500 w/ch into each speaker and it will see the combined load of the whole F208.

The BP17 is great with the 2.5, best match I had with those amps. There is a brand synergy there for sure. I haven’t heard the BP19 or BR20. The Benchmark LA4 is one of the best preamps I’ve ever had, especially as far as neutrality goes. It is a gem and at its price a tremendous deal. But for synergy with Bryston amps I’d probably get a Bryston preamp, if it were me. Plus as you mentioned you get the dual outputs.

Lastly, another option if you want to stick with Bryston and/or save some $$ and shelf space, the B135 integrated has preamp outs.  So you could use that with your 2.5B to horizontally biamp.  

The CODA 07x preamp also has dual XLR outputs (I think it also had an RCA).

It is a warmer tubey sounding preamp than the LA4. I kept the LA4.

My guess is that the dbx equalizer and sublime crossover have more to do with the lack of dynamics than anything else. These are both low cost devices with inexpensive opamps. In the case of the equalizer, you have dozens of opamps and cheap slider pots that you are running the signal through. 

@jaytor Yeah, I have always had concerns about the EQ. But some form of EQ is needed to help tame some of the FR variations from the room.

I have traps which are very effective. I don't need more, except for the floor to ceiling mode. But the "rules" prevent me from doing that. I have worked very hard at positioning the speakers and the sub to get the best FR, but there are still +/- 6 dB variations in the bass. I am restricted to near the present locations. I have tried a miniDSP Flex. It doesn't affect the time domain at all and is barely better than the analog EQ. I ditched that. And I enjoy the idea that I have an all analog signal path (except for the CD/DVD and music files).

So the dBx EQ is a somewhat "necessary" evil. I could live without it, but the engineer in me strives to have as perfect FR and TR (Temporal Response) as I can manage to obtain.

The XO does a very good job, far better than the Rane I once used. I don't like the idea of running the f208s full range and band limiting the woofer. However I haven't tried this in a while. Might be worth a shot.

Are you aware of any reviews on the Sublime XO?

Very helpful advice. Thanks.

@kevemaher - I suspect the crossover is not the biggest issue. I actually own a Sublime K235 (their newer model) and it seems pretty good although I don't currently have in my system. The graphic equalizer has many more lower-quality op-amps and capacitors in the signal path, so I think this is probably the bigger issue. 

If you really need equalization, I'd suggest looking for a decent DSP preamp, such as the Anthem STR or DEQX Pre-4.

Another option is the Danville Signal DSP Nexus. This isn't quite as fancy from a case-work perspective, and the software is quite complex (but there is good support), but the sound quality is pretty good using the latest AKM DACs. I also have a DSP Nexus 2/8 that I've been playing around with. 

And then there are the Trinnov systems although I don't know if their products support a phono preamp or even analog input.

After all this discussion of power, I bought a Bryston BP-17 cubed preamp. I'll get it next week. This discussion has convinced me that I have enough power from my power amp. So I decided to see if the much newer BP-17-3 can outperform the aged Levinson #38s. I hope so.