I think my Four 10 must have opened up considerably in the few weeks I have had it, with a gig and a couple of band practices. When I first got it I thought it was a bit of a "leveller" between my tube heads, as it imparted its own character on the sound and made the differences between the heads less apparent. I have really enjoyed the Trace Elliott V4 and the Orange AD200 with it, so tonight I went out to decide which head I would use this weekend - it was to be a toss up between the Super Bassman 300 and the V4B. I had a brief play with both and was really surprised by how clearly the Four 10 revealed the difference between the two heads. Tried the Orange and again clear differences were apparent. This is quite different to my impression when I played the heads (albeit briefly) through the cab when it first arrived so I can only assume it took a bit of playing to open up. All this is, of course, good. FWIW I will be taking the Super Bassman tomorrow. It was really tight, controlled and punchy with plenty of authority. The Orange AD200 was much darker in comparison. The strong midrange character of the Ampeg V4b was immediately apparent, although it could be eq'd out. I really was surprised by how strongly the Four 10 responds to the different heads, in a very positive way. I can't really pick a favourite combination yet, but I think the Ampeg will probably get least use with the Barefaced and will stay on top of its Ampeg 212av cab.
Not sure precisely how the cab has changed, I suspect the bottom end could be more extended albeit still very controlled and maybe (I hesitate to say this as it can be misinterpreted) a bit looser and more tubey but in a very positive way. I also think it may respond more to eq changes now, but that could be just me becoming more familiar with it. It certainly does not lack volume, I pushed the Super Bassman a bit and the cab seemed very comfortable. I wish I still had my old Ampeg 810 for a direct comparison as it did not seem any less dominant than I recall the Ampeg in the band room. Suppose I should have compared it to the Fender 810.