Here is a comparison of some of the amplifiers found on eBay.

I have been comparing the specifications of some of the amplifiers that I have worked with:

L-10 Amplifier:

Size: 200x41.5x?? mm

8 Ohm 100 Watts

4 Ohm 200 Watts

2 Ohm 350 Watts +-55VDC

Gain: ?? 

Output Transistors - 3 EA: A1943 C5200

L-15 Amplifier

L-15 Amplifier:

Size: 150x40x?? mm

Size: 5.9x1.57x??"

8 Ohm 150 Watts

4 Ohm 300 Watts

2 Ohm 600 Watts +-55VDC

Gain: 36x

Output Transistors - 3 EA: IRFP240/IRFP9240

L-20 Amplifier

L-20/28 Amplifier:

Size: 110x65mm (L-20)

8 Ohm 200 Watts +-65V

4 Ohm 350 Watts +-60V

2 Ohm

Gain: 34x

Output Transistors - 4 ea D1047 B817

Note: L-20-SE has 2SA1943 2SC5200 transistors

Note: L-28 Includes capacitors and speaker protection

PR-800 Amplifier

PR-800 Amplifier:

Size: 245x65x30mm (or 195x90 with 4 Capacitors)

Size: 9.64x2.55x1.18"

8 Ohm 500 Watts +- 95VDC

4 Ohm 1000 Watts +-90VDC

2 Ohm 1000 Watts +-65VDC

Gain: 40x

Output Transistors - 4 ea TTA1943 TTC5200

Note: Includes Capacitors and Speaker protection

Note there are 2 sizes; one with 2 large filter capacitors and one with 4 large filter capacitors.

NJW0281/NJW0302 Amplifier

NJW0281/NJW0302 450W+450W HIF

Size: 259x73mm

8 Ohm

4 Ohm 450 Watts +-85VDC

2 Ohm

Gain: Very Low - needs preamplifier

Output Transistors - 4 ea NJW0281/NJW0302

Note: ATX power supply pins fit the connectors on the right side.