I recently had to put mt Ampeg B4r in the shop for a minor problem (wouldn't power up) It was under warrany and has since been fixed. While it was in the shop I thought I would go ahead and buy a power amp to use with my SVPCL preamp. After shopping around I decide on a Yamaha P2500s. The sales brochure said it would do 1300 watts at 4 ohms bridged. Perfect, since I had been using the Ampeg B4r bridged at 1000 watts into my Ampeg 410he and svt15e cabinets. When I got the Yamaha amp home, I read the owner's manual and it said the minimum load in bridge mode was 8 ohms. emailed Yamaha and here is the response.... "Thank you for the email. The amp can be run at 4 ohms bridged but we do not recommend it. The 4 ohm and 2 ohm bridge specs in the brochure are primarily for comparison purposes. Many amp manufacturers will state that their amp is a very high rating but fail to mention that this is a 2 ohm bridged rating. Unfortunately, in order to compete we need to list these ratings also. Running any power amp at 4 ohms in bridged mode is very hard on the ampand I would question any manufacturer that gives the ok for this unless it is a commercial grade power amp or bass amp designed for this." So my question is, have I been wrong to run my Ampeg at 4 ohm bridged? Or is it a "commercial grade amp" where the Yamaha isn't?