I have two tube amps that I’ve built from kits. I use them in my basement jam space in a detached house. One is a 5E3 clone in a combo cab with a Weber AlNiCo and the other is an 18 watt Marshall clone with a modified TMB channel replacing the original tremolo channel. I play it through a Celestion Greenback in a closed back cab. I’ve found that circuit design has a huge influence on the ability of two similar powered amps to sound vastly different at low volume. Speakers as well. The 5E3 has large coupling caps that make it a darker sounding amp. It sounds great at low volume and can give a full sound with a bit of dirt. At high volume it breaks up of course and will start to fart out and get crazy; part of the appeal. The 18 watt sounds a bit sterile at low volume but really comes into its own when cranked up and holds itself together well; not a great low volume amp unless you’re going for a clean tone. So I guess what I’m trying to say is circuit has a bearing; not just wattage.