Well you & Les are definitely in the minority there, I agree with the majority view on this and have never been able to get a big amp at low volume to sound anything less than a bucket of fizz since 1981, and I've tried. The only other person I knew that felt that way was in a band with me decades ago, ............"it still sounds great man!!.........see?"..........well me & the rest of the guys didn't agree but at least he practiced.
Never did I claim this type of thing produces an awesome sound! Please don't misconstrue!
It's just that it sounds no worse than other solutions I consider
equally bad. I have a 100 Watt amp that switches down to 10 Watts, the Lone Star. It does what it does, but it doesn't sound much better at 10 W than set at 100 with the Master Volume simply set low.
My HXDA sounds better with the master set low than the Lone Star set to 10 Watts, frankly.
I've yet to play a 1 Watt amp that sounds good. The only 5 Watt amp that halfway works for my ears is the Suhr, and it's not all
that fabulous, though it is acceptable. As I said, I already have a 10 watt amp via the switches on my Lone Star that kinda sorta is OK.
In other words,
none of these solutions is ideal.
And of course, that's because of an inescapable fact: The speakers aren't being driven hard. The output tubes aren't being driven hard. The transformer isn't saturating. These things matter as much as power tube saturation to the sound of an amp. So the question is one of expectations; can they be met?
I made it very clear in many threads that I don't simply turn down my master; I can crank my amps to the max until quite late at night, and only need a load box or modeling solution if I'm working after midnight. When needed, I use a Cab Clone, and in another thread posted examples of it. The Cab Clone is itself an acceptable compromise. The Fryette Corey mentions is another acceptable compromise, as are modelers.
The point here isn't who's right or wrong; it's whether any black box is going to meet your expectations. I don't think you'll find anything that does precisely what you're hoping to find, but if you're willing to make the necessary mental shift in your expectations, you might find something that works for you. And you might not.
I've wasted plenty of time and money trying to find the perfect solution, and I learned that - for me - the perfect solution is an attitude adjustment. YMMV.