The blue channel with the gain low can get pretty fat if you keep the presence and treble in check. I've found some "odd" settings to be pretty good, such as turning the treble way down and presence up, or vice versa, to keep the cut. However even on the EL34 version it's not going to do that upper mid gritty crunch thing, it's just not designed that way.
I also love the green channel, unboosted, with the gain up a bit or even maxed out. It's looser feeling than blue but a similar core tone. Both blue and green share the same signal path just with a couple of switched values along the run.
Red has its own separate path with 6 (!) tube gain stages. Personally I really like Red but I've never really tried it for anything that wasn't high gain metal stuff or leads.
Thanks everyone!
It seems that most opinions center around the blue channel. And the red is just over the top gain and compression. Would a lower gain preamp tube in that slot help channel 3, or just neuter it?
I really gravitate towards 3 channel amps.
Contrary to popular practice, I'm not a big fan of boosting. The only amp I boost is my 800, cuz that's the thing to do. But still I always prefer amps that dont need it.
And it looks like the stealth doesn't need a boost.
You could try an ECC832 or ECC823 (sorry, I forget which one is which) in V1. V1A is used for the first stage of Red, while V1B is used for Blue/Green, so those tubes have a 100 gain factor on one half and only 20 gain factor on the other. Essentially you could leave blue/green untouched with the V1B side having the 100 gain side (same as a regular ECC83/12AX7) and the V1A side would only have 20 gain, and since that's the input gain stage it'll be a pretty noticeable effect on that channel. Whether it is a good effect is up to you of course. V2A & V2B are also only on the red channel so you could try something lower gain in there too, but either way that channel is always going to have 6 stages and the same shaping, so it'll have an effect but it may not be what you're thinking in your head.
I'm also not a big fan of boosting. I like an amp that *can* be boosted but sounds good without it, because I feel like I have two options. Same amount of gain/saturation but two different textures, boosted or unboosted (well, more than 2, since different boost pedals exist). The stealth isn't alone in not needing a boost, both the regular 5150 and EL34 version all have the same circuit and same amount of gain, with just a few different values changed between the models.