Hey guys, I'm having a problem with my Peavey 6505 head. Basically I was at my band's practice on Sunday and as I was playing the standby light had gone out and I had no sound.

i proceeded to switch off the amp immediately, and then turn it back on. I let the tubes heat up, then took it out o f standby. Still no sound or light.

The power tubes are fine, and it's not a fuse issue I don't think. I'm very confused/frustrated and any help on this matter is greatly appreciated!

I enjoy a hearty roast dinner...

...for breakfast.
Probably a wrong answer here but since the standby light doesn't go on and there's no sound maybe it's a preamp issue? I have no idea of the path of the circuit though
^ neither do I, I understand very little of electronics in general lol.
I enjoy a hearty roast dinner...

...for breakfast.
May be an internal fuse or a transformer issue.

Did you do anything out of the norem with it? eg. Try to use 2 amps or run 2 cabs?

Ohms all matched up? Are you the original owner or buy used?
A few things to check:
There are some fuses on the board on this amp, could be one of those.
The power tubes may have died.

However, this sounds like a power transformer. The standby light not coming on is not a good sign. Are the tubes getting warm/lighting up when you turn it on?
Does it hum when powered on?
Such is posting in Soviet Russia
Yes, I bought it used. I was running it at 8ohms through a fender cab of some sort (not my regular cab as I can't get that to our practice space) nothing fancy. The tubes get warm when I throw the power switch, but no action from the standby switch.

I've checked the main 5 amp fuse which is fine. I'm not sure where the others are. I will take it to my local shop asap, but I was basically to find out what it could be beforehand.
I enjoy a hearty roast dinner...

...for breakfast.
The fact that the light isn't coming on is probably good. The light is powered by the same transformer tap as the tube heaters, so if the tubes are getting warm but the light isn't coming on it means it's probably not your power transformer.

This sounds a lot like the HV fuse blowing, which is very good news for you. Hopefully that's the only thing that went wrong. Might have been a power tube shorting out, which would cause that fuse to blow. Even with a full retube, it's a cheaper fix than a power transformer.
That's cool, I'm going to take it to the shop tomorrow and see what's the best option in this case.

How would I know if a tube shorted out man? I assume it would not glow or heat up, all the power amp tubes are glowing.
I enjoy a hearty roast dinner...

...for breakfast.
It's unlikely, but it can light up when it's shorted. The short can happen across the plates or pins and the heater (glowing part) can still work. This sounds a lot more like an HT fuse though.