Bryston 7B3 vs 4B3: Extra Cost Worthwhile?

@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. 

@jfrmusic

Please take a look on the net for Krell Resolution 1’s and Stereophile review for the details. Difficult load yes.

I am suggesting you purchase an amp that will suffice for upgrades to come. The Benchmark is an excellent amp if you go that way. If you ever upgrade to speakers that will need a powerhouse amp then you have it with an entry level high end amp like an X350. If I were to redo my decision and stay away from difficult loads I would select a 50W/ch amp such as an old Krell KSA 80B and prepared for the high maintenance costs or something newer such as the Coda 5.5 which seems to have great reviews for price. To tell you the truth if these positive reviews continue for the 5.5 and they come back as no difference in sound bridged or not then I would definitely sell the X350.5 and get a pair of 5.5’s.

With your speakers no there will not be a super heating of the room. I looked, your speakers are a rather easy load to drive and even large scale orchestral won't cause any issues taxing the amp to create real heat. 

I hope people do not laugh hysterically before they try however if someone wants to try to see how to heat up an amplifier play The Key the Secret from Urban Cookie Collective 5 times one after the other and hop on it. Not to the point of clipping on transit but right there LOL. People can decide if they have the "powerhouse of the century" amplifier or not. This song is filled with information all over the frequency range, recorded in a bit of unusual fashion and a constant bombardment of power sucking requirements. If anyone can detect power consumption during playing please report back on that when the women only is singing.

Yes those Coda 5.5s look very interesting. I thought the same about bridging two. 

@jfrmusic I spoke with Doug at CODA earlier this week on bridging 2 S5.5's for my Yamaha NS5000. He said like most stereo amps bridging is not the optimal way to use the S5.5. He suggested another CODA amp for my speaker. That is a heavy one so not useful for you.

The Benchmark AHB2 is a bit better in regard to bridging a stereo amp. The AHB2 is unfortunately not a the very best match for my NS5000.