Would it sound the same with different couling caps?
Mallorys for coupling, spragues for power supply reservoir and cathode bypass. Silver mica for my bright cap.
Yes it would sound different with different coupling caps. You'll find - that there is a marked difference if you use Orange drops vs Mallory vs those blue Xicon caps. Reason being is what you hear goes through the caps, as opposed to signal being bled off with the caps. Also there is a matter of some AC current flow (DC blocked, hopefully). The current flow still rather small, but quite a lot larger than what you'd see on a guitar pickup. That is, in the amp you're seeing milliamps flow as opposed to maybe one milliamp if that, in a guitar.
I've not heard much difference in the power supply, bypass, and bias supply cap. I like the spragues because they're large, and take the heat well. For the bypass caps... any electrolytic would do (correct value assumed), but hey, I'm buying sprague, stick with it.
On the bias supply... there is a trick used to totally eliminate the hum from that supply. If you look at the common bias supply, its an AC tap from the main B+, dropping resistor (large wattage for heat and to take the higher voltage), diode to give you half wave DC, a reference resistor (or combined with a pot for adjustment), and a filter cap to smooth out the half wave. The bias still has a LOT of ripple in it at that point. What Fender did later on - a good mod - is make a normal traditional bias supply, but then, add another resistor, about 1k, and then another cap to ground, and then bring that voltage over to the grids on the output tubes. That second resistor and cap take out a lot of extra ripple, making it in the order of less then .1 percent residual hum.
But I digress... in guitars, use something thats the right value and fits the space given.