I use an original 1965 Deluxe Reverb with a strat (that has relatively low output vintage style pickups)...usually keep the amp on 6, and push it with a Klon Centaur cranked up pretty high. I'm having some issues getting feedback style sustain easily...I really have to keep my volume knob on 10 and get pretty close to the amp to get that kind of feedback sustain.... Tried out a 40 watt (I think) Fender Hot Rod Deluxe and was getting feedback sustain much easier, even with my guitar volume knob down a bit...The amp was set cleaner than my deluxe (my deluxe on 6 is pretty crunchy), and the perceived volume I set it to was probably around the same as my deluxe reverb in the room. Not sure if my issue with the Deluxe has anything to do with it's lower power output, or if this is a sign that I need to bring it to a tech and possibly replace the tubes (it's been a long time since I've changed tubes, can't really remember to be honest). Thoughts?