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Bryston: THX for 2 ch - a good thing or not?

Several Bryston amps are available with THX certification and badging at extra cost. Is this a good thing for 2 ch setups?
I recently had an email exchange with an Audiogon seller of a Bryston 8B ST amp. I told him I was also looking at two Bryston 8B ST THXs on eBay. He related to me an opinion he had heard that the ST THX versions were somehow inferior to the ST versions. Was he just hyping his amp or is there something to this allegation?
I googled this issue every which way without much satisfaction. One source mentioned that the THX stardard required expanded dynamic headroom, which sounds like a good thing, but doesn't the ST version also meet this requirement?
I spoke to a Bryston designer at the factory in Peterborough some months ago, before the current question became an issue for me. I got the impression from him that the THX versions were just the ST/SST versions with THX certification and badging, for which Bryston had to pay Lucas for the priviledge. Therefore, amps were certificed as THX compliant more for marketing reasons than due to any design modifications, except perhaps for some features (like a different input gain for the THXs).
Bottom line, is there any reason I should avoid THX versions for 2 ch listening? Are they better, worse, or just about the same?
russelllondon
russelllondon OP
4 posts
 
Bryston's online manual for the 3/4/5/7/8B STs includes drawings of the rear of the units, which indicate that the 5/8B STs have the power on/off function, whereas the 3/4/7B STs don't, and the 8B ST THX does.
The manual also refers to this function as being optional, so I suspect you could order it on a non-THX ST version.
A Bryston brochure also says "All ST amplifiers are available in THX version, include remote power on/off function."
The implication of this to me, as someone searching eBay, Audiogon, etc. for a Bryston power amp, is to make sure I ask the seller of non-THX versions if this feature is present or not. I have a Bryston pre-amp with it, so I would definitely want it.
The upshot is it seems I don't have to be concerned that the THX versions contain any design trade offs to comply with the THX standard that would effect my listening experience in 2 ch listening.
BTW I recall a posting on one of the forums where Tanner (Bryston VP) was commenting on a similar issue: the difference between base and pro versions. He said (in my own words from memory, since I can't find that posting right now) there was no fundamental difference, other than the pro version having a feature to attenuate the incoming signals to facilitate matching amp gains. He cautioned those who prefer a purer signal path (w/o attenuation electronics/switches) should stay with the non-pro version.
stevecham
3,340 posts
 
Remember the "Gold Record Award" label that was stuck on high selling LPs many years ago? These met the marketing ctiteria for units sold. Here we have amp specs that meet minimum criteria; same thing. Another stupid marketing sticker just like "digital ready" headphones and speakers.
pontifex
31 posts
 
10 years late but I feel like contributing my 2 cents to this thread.

I have owned the 7B ST's, 7B THX's, 7B SST2's, a 4B THX and a couple of very old 4B pros.

In short, I found that the Bryston THX amps performed noticeably differently than the non THX versions and is more than just a marketing scheme. 

To my musical tastes I would say the THX's sounded better. More dynamic, more weight in the bass, lots of midrange presence and I would even dare say a tad on the warm side. The 7B THX's drove my big subs way better than the 7B ST's. They had some serious punch.

Currently I have a 4B THX in my system and it is substituting for my Threshold T-400 which is in the shop for some repairs. Before I "Pass" my final judgement in the Threshold I will wait for it to return to my rig with a clean bill of health but for half the price the 4B THX could very well become my preferred amp. 
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