Above is a scan of a sticker SAE manufactured

SAE "PRO" Gear
SAE manufactured products (mostly amplifiers) to be used in a professional environment. These amps had a more robust case, front mounted gain controls and the ability to go to bridged mono mode just by using the proper 1/4 phono /XLR jack.

This is a set of the pro headphones

Be sure to click on pictures for full size

Here are some pictures of the F105 Forced Air Cooling System pro version of the 4301. It has the orange lettering to match the pro line of amplifiers. These are pretty rare too so the SAE god was looking down on me when this came along.

The P250 amp is the pro version of the 2401/A501. It too has 250 watts per channel in 8 ohms. It has left and right gain controls, XLR inputs in the rear and a more robust case.

The P500 amp is the pro version of the A1001. It too has 500 watts per channel in 8 ohms. It has left and right gain controls, XLR inputs in the rear and a more robust case.

Here is a picture of the rear panel. You can see how you can go from stereo to bridged mono just by using the proper jack. This was typical on the P50, P250 and P500.

Extreme right from my main system (SAE R-2 Rack w/ SR-10 Stack Rack extension) 

1. SAE Pro P50 Amplifier

2. SAE F105 Forced Air Cooling System

3. SAE Pro P250 Amplifier

4. SAE Pro P500 Amplifier