The HXDA is. a Plexi style amp, so I’m used to them, and here’s what you do.
Plexis overdrive quickly and that’s what causes them to get crunchy. When that happens, and an amp clips, the waveform is squashed and the amp compresses. Once the amp compresses far enough that it becomes saturated, the party’s over, because the signal loses top end definition due to the clipped signal; in that case, the amp won’t cut through the mix unless it’s loud.
Learning to control the way the amp saturates requires some old-school thinking.
Unfortunately, when you run its output through an attenuator, you’re adding even more compression, so it becomes more of an issue.
The less distortion, the less compression, the more headroom. A Plexi will cut for solos if you dial back the gain a bit, and control the amp with your guitar’s volume and tone controls. Set the amp up for a light, crunchy rhythm tone with your guitar volume halfway up, and you create headroom for solos using guitar volume and tone controls. As the guitar volume goes up, the amp gets both gainier and louder, and cuts for solos.
But you also have to let the power tubes do their thing, and that means giving it room to breathe. Yeah, it can get loud, but that can be controlled if you follow traditionalist advice on how to set it up. A Plexi isn’t a two-channel Mesa, where everything happens in the preamp.
What players did with their Plexis back in the day when they wanted tight lead sounds, was to dial back the gain to give the amp more headroom, and goose it with a fuzz.
Just my opinion, but using a tube screamer or other mid-heavy overdrive adds a more saturated, less distinct tone in a band setting, but a more full-range overdrive like an OCD works better. A germanium Fuzz Face style pedal and a Plexi is the classic combination, though.
A Plexi run a bit cleaner, controlled by the guitar volume, with a great fuzz, cranked so the power tubes are working? Hendrix. Eric Johnson. Duane Allman. Eric Clapton. Etc. And they all sounded different from each other, because they set things up to be what they wanted. I could go on, you know those tones.
Hendrix could play “The Wind Cries Mary” and “Manic Depression” with the same guitar, single-channel amp, and pedals. Kind of tells the Plexi story right there. Duane Allman used a Plexi and sounded completely different. That’s yet another tone story. Etc. It’s an amp that does let the player shape the tone, if the player ‘gets it’.
A true Plexi has only three preamp tubes; V1, V2, and V3 is the Phase inverter. It doesn’t have multiple gain stages. It’s simpler, and that gives it a certain character. Used right, it’s one of the greatest amps of all time. For anyone interested in its classic tones, there’s no substitute. And it isn’t a one trick pony. But you do have to learn how to use it.
Edit - One thing i forgot to mention earlier: bass requires the most amp power, so for more headroom and cut, turn down the bass control.
