Pass X150.5 or Odyssey Stratos monos?

I have been following this thread from the start.  As the OP stated, only two options were to be considered: Pass and Odyssey.  But there actually is a logical third option: Symphonic Line (SL).  Have a look at the link below and I will explain further.

http://https//www.theabsolutesound.com/articles/a-995-wonder-amp/

Jonathan Valin states that the circuit in the Odyssey is the same as in the SL RG-11, the lowest model in the SL lineup.  Maybe so, but that is where the similarity stops.  I have an older rev 15-20 years old) of the RG-11.  I borrowed a stereo Stratos amp a couple years ago.  I believe the Stratos was higher power rated, but the comparison was no match.  The SL had so much more clarity and refinements throughout it was not even close!  I honestly don't know how JV went so crazy for the Odyssey amp, and referenced h super-fi amps in his coismparisons.  The Stratos simply sounded like a budget amp to me.  And here I had a very early version RG-11, and it walked all over the nearly new Stratos.

I have no idea what is going on with SL amps, but they are just incredibly stunning.  I got the RG-11 for $700 a few years ago and I am absolutely positive that nothing on the new or used market can touch it for anything even close.   JV did mention it was 5K at the time of his review, and I can clearly understand why!  I have gone through a ton of amps trying to make my speakers sing.  Even the coveted Nelson Pass SA1 mono amps of years ago, that were able to drive the woofers of the Sonus Faber Amati speakers in a most awesome fashion, were easily outclassed by the RG-11 in clarity, tonal coherency and mid and upper-octave refinements.

I had heard of SL a few times along the way, but this little RG-11 amp can do a darn good job driving the big Sound Lab A1 speakers and could even make the SF  speakers sing fairly well too at medium volume.  Inserting the Stratos to drive the SF's, and the result was severely dimensionally flat.  So Rolf Gemein, chief SL designer, just does something special here.

I have since purchased a new version of the SL RG1 amp.  This is the next up the SL line, and it has much more capability to drive my speakers to impressive levels.  And it brings on a much more refined portrayal of space.  A shoot out with the big BAT amps gives the pros and cons of refined detail and finesse of the SL vs. the big bold powerful BAT.  I can only dream to go up another level or two within SL.

So @whatsmyname, yes, I suggest that you do indeed call Klaus at Odyssey?  And why do I say this?  Because he is the SL distributor in the US.  There is a good chance he might have an SL amp for you to audition.  And the SL will give the Pass a serious run for the money, and likely take the checkered flag.

Hi George,

I think I see what you are referring to in the photos. In the mono version there is a sleeving containing a red wire and a yellow wire, which appear to connect the amp’s output connectors to the printed circuit board. With the red wire going to the part of the circuit board that is associated with one channel in the stereo version, and the yellow wire going to the part of the board that is associated with the other channel in the stereo version.

Which is suggestive of a bridged design. However I suspect that the two channels are paralleled, rather than bridged. With one wire, probably the yellow one, going to circuit ground, and with a connection between the outputs of the two channels being made somewhere where we can’t readily see it, perhaps underneath the board, and in turn connected to the red wire.

As you know, bridging can potentially increase power capability into 8 ohms by 4x (i.e. by 6 db), although most bridged designs fall somewhat short of a 4x increase due to current and/or thermal limitations. But in this case the increase in 8 ohm power capability of the mono version relative to the stereo version is almost negligible (less than 0.8 db). And as you indicated bridging reduces damping factor, while the damping factor of these monos is substantially higher than the damping factor of the stereo version.

Also as you know, paralleling can potentially increase power capability by 2x, while increasing damping factor rather than decreasing it. But IMO it doesn’t speak well of the robustness of the power supply and/or other aspects of this design that the mono version only 20% more powerful into 8 ohms than the stereo version.

In any event, it’s really a moot point as far as we are concerned, as you, I, and several other posters recommend going with the Pass amp whether the Odyssey monos are bridged or paralleled or something else.

Best regards,
-- Al

As you know, bridging can potentially increase power capability into 8 ohms by 4x

Just not to confuse others "power" is "wattage" only in this case, current is halved.
And yes Al I agree, Pass amp by a long way.

Cheers George

I'll go with the Pass as it's a respected, musical, quality amp. No offense to Odyssey - I was curious if it was close enough as it would allow me to get more power for the money. @jafox I'll check out the SL amps out of curiosity. Thanks.

Personally, I have owned 2 sets of Odyssey Monoblock Amplifiers. They were enjoyable, yet both sets were sold. No plans on buying more. I have never owned a Pass Labs amp. It sounds like they are the real deal. If the Pass Amps are anything like Balanced Audio Technology Amps, I can see the attraction.