I am using a very old Mesa Rectifier 4x12 which is loaded with Black Shadow C90 speakers (Celestion-made, don't know what original Celestion model they are based on). The cab is larger than a Marshall 1960, slanted and has the Rectifier design (logo, leather-type "skin"). The sound is pretty mid-heavy and a bit harsh in the 3000 Hz area. My amps (Marshall 6100, Bugera 6260 mainly) and guitars (Gibson Les Paul /w Burstbuckers, Charvel 750XL /w EMG 85/89) are mid-heavy as well, so the mid-stuff seems to pile up. I am thinking about swapping one or two speakers with Vintage30's for recording, but I don't know what change in tone I can expect from this change. Can anybody tell me what I can expect?