Well, as a huge Mesa fan I am somewhat ashamed to admit that I was unable to follow agedhorse's sage advice from a previous post exchange. For some time I had been searching for a clean used Scout extension cabinet to add to my Scout 12 combo. No luck on that so my next option was a Subway 1x12 cabinet, which agedhorse said would work. However, that would have required me to replace the original 4 ohm speaker in the combo with an 8 ohm version. That, combined with the cost of the Subway cab just wasn't in the cards at the moment as yesterday I just had very expensive oral surgery which negated large gear expenditures for awhile.
So, in a fit of experimentation, last week I ordered a new 4 ohm Eminence Kappalite 3012LF-4 speaker. 550W RMS, 1100W Program, 9.1mm Xmax. Yes, I know this speaker is primarily meant for PA/Subwoofer use but the stats looked good to me and I figured it was worth a try.
Well.....to make a long description short, it is stunningly AWESOME. The low end is incredible for a 12, the mids are great and with the horn turned up to +2dB and the passive radiator radiating, there are actually sparkling highs even with a P-bass with TI flatwounds. I am completely blown away and there is clean headroom like never before with this setup.
This is an older silverface Walkabout with the Rhino Tolex but it did come with the active/passive switch. I've had it since new - 11 years or so - and it has been 100% reliable. I did install new preamp tubes last year which sharpened up the tone. I gigged it a few times early on (through a pair of PH 1x15's) but as a combo it has been mostly a studio and jamming amp. I've always though it was a great combo amp but with after the speaker swap, it is now an incredible amp, combo or otherwise. Not as loud as my D-800 but WA tone is unmatched. Especially now.