I think that the Blues Jr. is only a so-so-amp. UGH. What I strongly dislike about it stock is the design of the preamp. You can turn up the pre gain all the way and at low volumes get only a bit of grind. You have to turn one up pretty **** loud to get it to grind well.
Shredd, there are SO many good boutique amps out there. I think that a far less expensive and believe it or not, easily as good sounding (in its own way) alternative to you former 2 channel recto head would be a Bedrock head. I have a 651 50 watt 1/12 that I got on ebay delivered for 660 fom Canada in a wooden shipping case the seller custom made for it... That Bedrock is the same size or slightly smaller than a Blues JR. 50 watts sings/sustains for days, and after my typical revoicing with VOS tubes it will hold its own with extra for any 50 watt 1/12 amp out there, has Brit sounding tone. Has great gain/sustain even at bedroom volume. The head models, 1200, 1400 etc. can easily compete with ANY Mesa 50 watter volume wise and still have some more in reserve, They truly are monsters, hardly anyone knows about them, and the old ads say "The tone that kills." They were right. The transformers in all of the Bedrock amps from beginning to end of their production are rated for double the amps capacity, the tones are huge due to the oversized OT's they used. Today's amps like the Blues Jr. use wimpy iron. Hence the wierd mid honk, there is less bandwidth available from that wimpy OT. Wimpy iron=wimpy tone. The 20 watt Bedrock 621 1/12 will wipe the floor with a Blues Jr. and that 651 50 watter will absolutely bury one. el84 power section on these like the BJ has, ss rectified, the fx loop has send and return pots, enough boost capability as the result of that to amaze you and bandmates. Bedrock was boutique before boutique was cool, now they don't make them any more, bad market timing.