All things being equal, my bias would be towards monoblocks, but why take someone else's word for it? ;-) PS Audio offers free in-home audition of their products if you contact them. Likewise, Mark Sammut at Reno HiFi (renohifi.com) can arrange a trial of Pass Labs amps. In this case, he will pay shipping to you, but you have to pick up the return shipping costs. I own products from both companies (direct from PS Audio and through Mark in the case of Pass) and both know hot to make customers very happy.
Forgot to mention that Reno HiFi makes a market in demo and used
Pass gear (which include current production models). Considering such
could move you up the Pass Labs amplifier food chain to a very significant
degree while staying within your budget.
Demo
usually means the gear has been unboxed and played for a month or two (you
essentially get a pre burned-in amplifier), and these units come at a
significant discount with the balance of the factory warranty. Some of
the used pieces have been "refurbished" at the factory to make sure they
are performing to "as new" specs and come with a 1 - year warranty.
Best
of all, Mark will buy back anything he sells you towards future
trade-ins. I've been a happy camper customer for over 15 years and have
bought and sold my way through 4 Pass amps and 3 preamps with Mark
while working up to my current system with XA point 8 monoblocks.
Wish I could comment on the Pass Labs gear, as it certainly enjoys a great reputation, but, alas, I have never had it in my system (well, an Aleph 0 back in the 90's!). I can vouch for the PS Audio BHK 300 mono's, which I have been using for ~2 years now. They are very nice amps, IME, and they run my TAD CR-1's beautifully. I think you cannot go wrong with them (and the 6922 tube input for system "tuning" is a very nice feature). Just my 2 cents.
By all accounts Bascom King did a masterful job with the BHK amplifiers. Pass Labs has earned an esteemed reputation. I’d audition both of them at home . I don’t agree that Pass is a no brainer choice compared to the BHK. You must listen and then decide preference. Charles
Pass amps are in their third generation, designated "point 8," so the stereophile review of the "XA-160" is fairly dated. Here is a more recent, direct comparison of the Pass XA160.8 and PS Audio BHK 300's by Tony Cordesman: http://www.theabsolutesound.com/articles/ps-audio-bhk-signature-300-mono-power-amplifier/
Spoiler alert: he keeps the BHK's as a second reference. (Must be nice).
Note the Pass X- series operate for the first few watts in class A and then transition to class A-B. The "XA" amps are single-ended class A throughout their rated operating range. The two designs have different - but still excellent - sounds (the X series being a bit more "punchy" and the XA's more "tube-like"). If you poke around on the Pass website, there is a technical paper by Nelson where he mentions how customer preferences for the sound of his designs relate to residual distortion products. Fascinating stuff.
You have a tough choice. King and Pass are both legendary designers. Gotta listen for yourself.
Thank you everyone. Believe it or not BOTH deals fell through one of which was as a result of an unreliable seller- but so be it,
If I may, do you have any thoughts about Quicksilver V4 mono's? I have always wanted to try tubes with the Thiels. I will probably contact Mike Sanders in the morning.
@Unsound- I generally do not listen very loud although sometimes I do crank the music up (80db or so would be my guess for an upper limit) and I sit some 10 feet away from the speakers.
it would be a very far stretch- used single units range around $4k (give or take $200)- and there’s the matter of finding 2 of similar age and tube usage. I was originally looking to spend some $5k for solid state- i realize tubes would be more but 8 really do not want to go much beyong $6k.
Quicksilvers V4’s have a very good reputation - i know of several audiogoners that swear by them- and are hand wired for much less (mono’s) but of course the transformers are key.
And FYI I just spoke to Mike Sanders- it was a pleasure and he in fact discouraged using the V4 with the Thiel 3.7's (which he seemed quite familiar with). The source impedance of the amp is too high and would not match with the speaker's fairly impedance dips.
This is something that unsound had been mentioning.
On the other hand he explained that the mono 120's are specifically designed for more difficult loads and should handle the Thiels well.
One of the problems of course is that this kind of information rarely readily available unless the amplifiers have been reviewed and appropriately tested.
I want to look more into this- very interesting. I just wonder what kind of output impedance would then be considered a good match- yes obviously the lower the better but that is just a relative comparison. I would like to know about the matching in more absolute terms.
Keep in mind that the Thiel 3.7's don't just dip into sub 4 Ohm loads, they live there over most of their operating conditions. That's why I caution those to be wary of amps that merely claim to be "Stable for musical transients". Thiel's recommended power was 100-600 Watts per channel, but that was for a standard 8 ohm load with the understanding that the amp would double down as needed into the actual load. Into a nice, safe rounded 2 Ohms that would be closer to 400-2400 Watts. Keep in mind that as the impedance drops so does the sensitivity. So that 400 Watts minimum might seem like an awful lot, but, for adjusted sensitivity; it's about the same as 100 Watts into 8 Ohms. Some of the amps you previously mentioned are indeed robust, sturdy amps with most speakers and then some, just perhaps not ideal into your particular Thiel 3.7's.
I couldn't find more recent independent measurements of Pass Labs current offerings. While I suspect the more recent ones might be better in this regard, I also suspect that these older ones are not irrelevant. As much as I like some of their gear, their independent measurements have been somewhat disappointing of late.
I tried to include this before but for some reason it wouldn't take.:
I've been a Professional musician most of my life and you must ask yourself, am I a music person, or a gear person? Every audiophile should know by now that sound signature is subjective and personal. The only true way to know what's best, is to know what sounds good to you, and that's all that matters IMHO.
I use a Pass Labs X150 and two First Watt F3s to power my DIY horn speakers. In my estimation Nelson Pass is a genuine genius. You won't go wrong with Pass.
Sorry both deals fell through — that sucks. As another potential option, McCormack and Thiel have always made for a synergistic pairing, and there’s a nice DNA-1 on USAM for around $2295 that’s probably negotiable as it’s been listed since mid June. It has SMcAudio’s “Silver Special” upgrades I’m not familiar with but seems to incorporate many of his latest mods. You could ask him what it has and what’s left that could potentially significantly improve the sound further (Gravity Base is likely one), and even after doing any remaining mods you’re still probably around $4k all in and you’ll have one great amp. Power shouldn’t be an issue as it doubles to 300Wpc into 4 Ohms and puts out 500Wpc into 2 Ohms. Of course since it’s already got a significant amount of their mods you could just enjoy it as is for a while and upgrade later if you start to get “the itch,” and it’s nice to have the option of getting even more performance down the road. Anyway, just another option to ponder, and best of luck in finding a great amp for those great speakers.
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