Anyone heard of AVITEC PRO amp (old!)

[digitallake]

Hi, just wondering if anyone has any info or has used a power amp made by AVITEC, model PRO BETA 500 I have just been given one I don't know if it's any good or whether to strip out everything apart from the power supply and build a new amp into the (rather meaty) rack case. I've tested it and it appears to be OK although there is a bit of mains hum and a couple of other minor issues which can be fixed....in listening to it I can't tell the difference between the sound quality of this amp and my "other" amps at medium volume levels. The amp is quite old (probably getting on for 20 years!) and looking inside revealed power transistors I don't recognize the numbers of, bolted to what seem like SMALL heatsinks for the the specified output power (250W per channel) but there is a very large fan!!! Hmmm.....can't find any reference to this amp or the transistors on the 'net - any ideas? Cheers!