absolutely not... that's not what it is... it is a guitar amp.
i'm sorry... but plugging into an amp... is very different than monitoring a studio style feed...
not to mention that the volume changes our hearing perception... so simply playing at volume, and playing at low volume itself... is a very different experience.
it's a guitar amp... and your attempt to use it some sort of a monitor... well that's simply not its intended use... there is no versatility in the design for that...
sounds like the amp is simply not a good fit for your needs... if you need a PA/Monitor solution.... find one.
don't mean for this to come off snarky... just putting it all very plainly...
and from the sounds of your concerns, my opinion is that you simply have the wrong product for your needs.
I appreciate your point of view but disagree with some of it.
In LVM with full amp patches the setup (podHD + DT25) is an all digital, pure modelling rig. According to all official and forum logic the tubes and analogue circuitry are being bypassed.
IMO it should therefore function like a digital amplifier in that the signal should be identical to the studio monitoring signal via headphones, with volume adjustments possible from very high to very low not affecting tone (other than the effect of volume on hearing perception as you point out). This, I assume, would be the case if I used something like an L2t as a speaker.
The difference I am hearing with and without L6 connected is night and day. As I say, almost like a raw line out signal. Line 6 advertise this aspect of the rig (LVM) as allowing "whisper quiet" practice all the way through to stage volume. Mabye, but seemless and effortless it ain't. In terms of practicality and effort required, I might as well have 3 different rigs for quiet, medium and loud volume.
I agree though that the DT25 probably is the wrong product for my needs at present.