I had the opportunity to play on an old Marshall JCM 800 50 watter the other day. I ran it through a Mesa Boogie Rectifier 4x12 cabinet with Vintage 30s. This particular amp had been collecting dust and hadn't even been turned on in over 20 years. We were working on preproduction, so I didn't actually put any mics in front of the amp. I just played on it.