Amp Comparison procedure. Amp off when not in use?

We will be conducting an amp comparison this weekend between two solid state amps. Couple basic questions:

Would it be OK if we leave the amp on when we don't have any input/output connected to it to keep it warm? If so,

What is the best way to unplug? Remove speaker cables first, then remove input cables?

What is the best way to connect? Input cables first, then speaker cables?

Or would it be safer to turn off the amp completely when it is not connected to speakers?

Turn the thing off.Better safe than sorry.
I don't see any problem with leaving a totally disconnected solid state amp powered up. But connecting or disconnecting either its inputs or outputs while power is on strikes me as an invitation to disaster, especially if the inputs are unbalanced rca's (which make the ground connection after the "hot" connection during insertion, and break the ground connection first during removal, thereby potentially injecting a huge transient into the amp's signal path).

I would strongly recommend that before changing any connections you power down both the amp and the component driving it, and then wait a minute or two for the amp's power supply capacitors to discharge. The couple of minutes that will take should allow the subsequent warmup to be brief.

-- Al
Thanks guys for the quick responses.


Another question. So the amp is connected to the preamp via a pair of balanced interconnects. Would it be OK to leave the preamp on, but put it in "Mute" mode? the preamp is an ARC LS-25. My friend is bringing over his Spectron amp to compare to the Pass X350.5.

Hi Frank,

Yes, I would think that would be ok, given that the preamp will not be putting out a signal (due to the muting), and given that the interface is via xlr's (which are designed to make the ground (pin 1) connection first, and break it last).

-- Al
And don't forget to post your opinions after the shoot out.

Take notes! Play familiar stuff.

If you can position the secondary, or in question, amp close to the present main fav, the interim time frame will be shortened and should help. Naturaally too, if the 'B' amp is also on during the note taking on the main amp, the warm up time will be further shortened... However do connect a load to the 'just hanging out' amp while it's on.

Stepping outside for a few minutes too will help you refresh your ears... then go in and sit down to audition the other amp.

Those would be my thoughts, but the note taking is KEY.

Good luck.

I disagree with the note taking. It should not be done at all but instead they should try to get into the music and forget everything else and sonic issues will present themselves.

Best to leave the conscious mind out of the equation and enjoy as much as possible.

I am sure I am leaving myself open to commentary with this remark!



Philjolet, it sounds as if you listen as I do, let your whole mind experience the sound. Experiencing sound and analyzing it are two different processes, try to see if it sounds "right" to you first and then try to discover the reasons later.