new GAN amplifier

Many (me included) just don't like Mosfet sound. 
 Listen to some older Threshold Pass amps that used bi-polars, you'll change your mind.

Cheers George

Also note this difference between the two taken from a seminar on Mosfet V Bi-Polar (BJT), which to me gels with what I notice/hear.

"BJTs tend to have better, more linear gain characteristics…and can give you a lot higher voltage gain than MOSFETs.…They're also able to handle higher output currents…and have a lower output impedance.…That gives BJTs a huge advantage over MOSFETs…for building amplifier circuits…that need to provide a significant amount of output power…and or drive loads that have low input impedance.…MOSFETs are going to have a harder time…driving a low impedance load…because they have a higher output impedance.…"

Cheers George

I am going to go out on a limb and say you wouldn't know without being told if the amplifier had FETs, BJTs, etc.   Topology is going to make far more difference to the sound.

Maybe, if those listeners don't know what to listen for.
But for those same listeners short term living with each amp, listening to many albums over a few days you eventually would pick it, especially if the speakers are hard to drive.

Cheers George

How can you know "what to listen for" wrt transistor type when you don't even know the underlying amplifier topology and distortion mechanisms, intentional voicing, damping versus frequency, bandwidth, etc.   You simply can't.  You can't take something you heard on a limited set of products and apply that to all products.