If the amp was cutting through too much (from the sound man's perspective) put the mic off axis, like way off to the edge of the speaker cone. That right there can make more of a difference out front of the PA than even the bright switches on the amp. The difference between an SM57 centered vs way off to the edge is NIGHT and DAY.
I've had gigs were the PA was so bright that I miked my 4x12 with the mic right under the last L in "Marshall" (small logo) which is barely on the edge of the cone. That said, I recently did a gig where with the mic dead center on the cone it was too dark out front (with the board channel flat) so it really depends on the PA. That was with EL34s and the full bright switch position. Still I run two 18' cords in series, a THD hotplate, and a few layers or felt over the fronts of my Scumbacks under the thick basketweave cloth ALL of which darken things up for sure.
I find with a small 1x12 the bass is so limited that the treble needs to be cut even more to balance the spectrum. I run 2 to 4 layers of felt over my M75s, those that are in 1x12s that is. It seems the less bass you have the more the treble get's out of balance and needs to be cut somehow even more.
Also a fairly fat sounding mic like a Sennheise e906 helps, and also I find 6V6s in a wreck as thinner sounding the EL34s so I never use them.
Also for the bright cap to be pleasing you need the amp volume up at least half way with most potentiometers that is. Any lower than that and the bright cap takes over.
Speaking of a blanket over the cab. I've done quite a few gigs where I ran a very small sealed back 1x12 at the front corner of the stage on a bar stool aimed back at me at an angle. Then I also run a 4x12 behind me miced with a Sennheiser e906, put a Tuki padded cover over the cab and left on all night. The flat profile mic really helps with this. Anyway I can hear myself with plenty of articulation via the 1x12, and I still hear some deep thump from the covered up 4x12 so it still sounds fat on stage. With this setup there is barely any forward bleed and it still sounds like a 4x12 out front. This is with a 16 ohm 1x12 in parallel with the 4x12, which with the somewhat inefficient small 1x12 I can get away with this setup only using about 4db of attenuation and all speakers M75 Scumbacks. I should also mention I typically prefer a THD hotplate, though I'm on the list for a Phantom. I owned a Dr. Z airbrake and never liked it at all with my wreck, too bright and shrill. The THD darkens the tone a tad and that works just fine, as long as I don't go down passed -8 which I almost never need to do.
Speaking of soundman I do plenty of gigs using one of my clones and through my own PA system. My PA has a total of just 4x12s for FOH though plenty of clean power. Two EV 1x12 SX300s for top cabs (with 1200 watts on them) and two Danley single 12 TH-mini subs (with 2500 watts on the pair). This PA easily allows me to run my Trainwreck clones in the sweet spot and still mic them though FOH, along with some nice fat drums, and of course vocals going over top all that! That said in really small rooms where folks may be sitting really close I use the padded cover trick I mentioned earlier. On larger stages I can still run -4 on the THD but skip the padded cover trick all together.
I also agree that if you have a powerful drummer a Wreck on a 1x12 only goes so far. It does depend on the speaker though. I can say that for comparison sake that with old G12Ms in a 4x12 I found that a Liverpool was not even enough with a strong drummer, at least for the clean tones and that's with a 4x12. I could see how on a single 12 an Express might not even need any attenuation if you have a heavy handed drummer, and a lower efficiency speaker. G12M speakers (my fave) are a bit less efficient than alot of other speakers, and they are even a tad quieter than M75 Scumback recreations which though they are obviously similar sounding seem a little louder. Also the OT in an Express can make a big difference. I find the Pacific 6.6k OT makes for a quieter and slightly darker amp. Heck my original with EL34s is quieter than a typical 5.2k Ceriatone is with little 6v6s!
Sorry for the long post, I'm a "sound man" also...
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