It depends on your guitar. If it simply has pickups and passive switches, tone controls etc, then plugging into two amps in parallel will load the pickup more than it is expecting, so you may not get the sound you expect from either amp. If the guitar has active pickups and a preamp built-in, then it should drive both external amps OK.

I suggest what you do is set up the amps with the splitter lead, have both amps switched on, but one of them turned right down. Don't plug the lead into this amp yet, and adjust the other amp so you get the tone you expect from it. Now while playing, have someone else plug the lead into the quiet amp and see if it changes the tone from the loud one. Do the same with the amps exchanged. If you can't detect differences in guitar tone when the lead is plugged into the other amp, you're OK. If there is a difference, judge whether you can live with it or correct for it on the amp's controls.

What else could go wrong? Well, I think I would try plugging both split leads into the two powered amps before I connected it to the guitar, just in case there was some horrible live ground effect. Also, remember that the overall length of lead can be a factor, so don't use excessively long splits. It could be that you get an unacceptable hum level from one or both of the amps when they are paralleled with the splitter lead, in which case you may have to re-think the arrangement and try using DI boxes or something similar.

Either way, it sounds an interesting experiment. The next question is how to mike up two cabs playing the same material to avoid sound bleed...

Edit: double post

You don't list the amps that you are wanting to do this on, so this may or not pertain to your situation, but....
If at least one of the amps has a PAIR of 1/4" input jacks on the same channel (like a Marshall JTM or a Fender Twin), these are actually parallelled together. Plug the guitar into one of the jacks, then run a shielded guitar cord from that 2nd input to the input jack on the second amp you want to use.This will feed both amps. Try to use as short a cable as possible to prevent RF noise pick-up. Certainly not high-tech, but it has worked many years, for many engineers, many players. It's how all those Marshall stacks of Page, Blackmore, Hendrix, Clapton,etc., got strapped together. I typically parallel 2 or more amps together, it's great fun for the entire family!

i have a A/B/Y switch. that way i can pick either amp or use them both at the same time. Morley makes one and i have an ART one. i think their about 30-40 bucks.

You don't list the amps that you are wanting to do this on, so this may or not pertain to your situation, but....
If at least one of the amps has a PAIR of 1/4" input jacks on the same channel (like a Marshall JTM or a Fender Twin), these are actually parallelled together. Plug the guitar into one of the jacks, then run a shielded guitar cord from that 2nd input to the input jack on the second amp you want to use.This will feed both amps. Try to use as short a cable as possible to prevent RF noise pick-up. Certainly not high-tech, but it has worked many years, for many engineers, many players. It's how all those Marshall stacks of Page, Blackmore, Hendrix, Clapton,etc., got strapped together. I typically parallel 2 or more amps together, it's great fun for the entire family!

I'll just add that I don't think the splitter you pictured would be the right one to use. It shows a TRS male end, then on the female ends you can see one says TIP, you can bet the other one is the RING. This is to split a stereo signal into separate left and right mono signals. If you were to use a splitter like this, I think it should be a MONO male end (your guitar's output jack is most likely TS mono, unless you have active pickups you may have a stereo jack where the extra terminal engages the battery).

If you don't want to buy an amp splitter box, or an A/B/Y box, you can use a mixer if you have one lying around. Plug your guiter into an input and plug your outputs into the amps.

Ballz wrote:

If you don't want to buy an amp splitter box, or an A/B/Y box, you can use a mixer if you have one lying around. Plug your guiter into an input and plug your outputs into the amps.

i had actually thought about using my peavey mixer to split the signal as well. does this work pretty well?

I'll just add that I don't think the splitter you pictured would be the right one to use. It shows a TRS male end, then on the female ends you can see one says TIP, you can bet the other one is the RING. This is to split a stereo signal into separate left and right mono signals. If you were to use a splitter like this, I think it should be a MONO male end (your guitar's output jack is most likely TS mono, unless you have active pickups you may have a stereo jack where the extra terminal engages the battery).

If you don't want to buy an amp splitter box, or an A/B/Y box, you can use a mixer if you have one lying around. Plug your guiter into an input and plug your outputs into the amps.

Friends don't let friends use Peavey mixers!
Seriously, that's the sure way to kill the tone of a
passive electric guitar. None of that mixer's inputs are really designed for that. This has to do with operating levels and impedance loads. Steer clear.
As to the A/B box, always test it out with your amps, some of them are prone to "pop" noises when they switch (they shouldn't, but...).

I use two amps playing live sometimes and I use a Whirlwind selector. Works great, no pops when switching amps. No noise at all. I have been very pleased with the whirlwind. It's not cheap.
About 80 bones.

Like moonbaby said, The cheap ones will pop. They can cause damage
to your amp or speakers.

Peace...........Scoobie

A high quality, budget, or free active splitter can be had by using one of the stereo pedals one has laying around. Just set the pedal to mono, or turn the effect off.

The Boss twin pedals like the DD20 delay have really quiet high headroom buffers(line amplifier stages) in them. Plug into the input, and get two buffered outs good for longer runs too. Put a high quality (four bucks) switch in a little box and you can turn one output on or off.

Live, I use this setup with a volume pedal instead of the mentioned switch. It goes to my ratty sounding little '60 Valco tube amp to bring out some trebely presence when appropriate.

I'm sure everyone has something laying around gathering dust they can try.

T.P.