This actually exactly how I use my compressor lol Even a well made tube amp can feel "choked" at volume 4 out of 10, so I use a compressor pedal to simply add that "cranked to 10" feel without changing the sound or character of the amp, nor does the compressor alter the dynamics in any way. The compressor can even boost the signal and push the amp. Even better if it's a footswitchable boost like the Wampler Wong Compressor FET boost or the Pigtronix Tone Philosopher 2 Germsnium/Silicon boost.
If you want a "MORE" option without adding sustain and without altering sensitivity, as Andy Wood, Shuan Tubbs and Andy Timmons calls it, a simple clean boost pedal would do.
While it's true that overdrive pedals were originally meant to simply overdrive your amp, today overdrive pedals are really used to change the amp to a desire sound. A Fender amp can be made to sound like a vintage Hi Watt, your ears wouldn't be able to tell the difference. Players now days seek to have different pallet of sounds available to them, it's great as long as it doesn't get muddied or get lost in the mix.
I use a Marshall JTM Studio which is Marshall's pedal platform flagship amp. Every pedal sounds great on it regardless of volume, if I use a "Marshall in a box" type pedal, it sounds amazing on it where as it would sound terrible on something like a Marshall DSL40. So it depends on the amp, speaker, pickups combination as well.
Out of my many years of touring and working in the studio, so far my JTM Studio is the only amp I've played through that sounds exaxtly how I want it to. I am a pedal player though, so a 1 channel jumpered low wattage tube amp is a dream.