Bryston 7B3 vs 4B3: Extra Cost Worthwhile?

How warm does the Pass 350.8 get?  Don’t want something hot to the touch or warming the room..

The 350.8 is absurd for your speakers, and the 150.8 would be more than adequate.  Moreover, Pass has a different sound signature from Bryston — they are not substitutes.  Figure out what sound characteristics you want first, find a brand that exhibits those qualities, and then pick the model with adequate juice to adequately power your speakers.

Sorry to disagree. There is no amp that is absurd for my speakers or any speaker of high quality. There is no such thing as too much power. I believe the Pass 150, 250 and 350 are  excellent amps. I will audition them. But was interested in how warm/ hot they might become over a long listening session. Power is not just for driving loud volumes. It dynamically controls the speaker and provides reserves for dynamic peaks especially with large scale Classical  Music which I Listen to. 

@jfrmusic When the X350.5 turns on it draws 600W. After that it depends on what I do with it. If it just sits there it will be warm to the touch on the fins but that’s about it. I don’t have a problem grabbing them with pressure and it’s not hot at all.

Here is when it does get hot. When I drive difficult loads. Below I copied and pasted the impedance details of the speakers I am using now. I do hop on the volume control I can assure you and when I do the X350.5 does get hot however when I drive my PSB Stratus Gold i’s with authority the amp does not get nearly as hot. Here are my speaker impedance specs.....

As can be seen in fig.1, the impedance remains at or below 3 ohms for two-thirds of the audioband, relieved only by the reflex peaks in the low bass and a region between 4 and 6 ohms in the upper midrange/low treble.

Compounding the drive difficulty of this low impedance is an electrical phase angle that varies considerably. So not only is the minimum impedance a current-hungry 1.8 ohms at 58Hz, this is combined with a phase angle of –25 degrees. And a little lower in frequency, even though the impedance has risen to a more manageable 3.8 ohms at 43Hz, the phase angle is now –61 degrees

The Pass Labs X350.5 is on a completely different level from Bryston in every respect. Both the X350.5 and the 4B3 are about the same power stated but completely different leagues when it comes to smoothness, effortlessness, bass grip, dynamics and what the recording really is. If large scale classical is on your list like mine the extra power is a GOD sent. As I turn it up the effortlessness does not change unless the music I am listening to gets so aggressive (lots of information such as bass pedals, drum roll and bass guitar hit with an open E) and volume so high that short passage will compress up a bit. With the Bryston as soon as I ask for more than maybe 10W continuous it just starts compressing the sound and the number one reason my friends all use Bryston on secondary systems. Thing is though even my friends that use them for DJ’ing and such have never had an issue with them which is a true testimony to the amazing reliability of Bryston power amps.

Pop the top of both the X350.5 and the 4B3 and see what an amazing difference there is between the two.

@piebaldpython 

Thanks for the info. Unfortunately your specs didn’t show. From what you stated I might expect my easy to  drive 6 ohm Harbeths ( lowest impedes 5.2) to not cause significant temperature issues with the Pass.