This Onkyo TX-2500 receiver is a low to mid-range offering from Onkyo with the TX-8500 being the big dog at the time. I’ve always liked the look of the Onkyo receivers – even the bolt on front dial glass. When all the bulbs work and they are lit up they have the warm glow of candle light. This particular TX-2500 is the MK II version which does differ slightly from the regular TX-2500. I believe the TX-2500 came out around 1976-77 and the revised MK II around 1978. The MK II had a retail price of around $360.00.
Onkyo’s TX-2500 is listed at 27 watts per channel while the Tx-2500 MK II is listed at 40 watts per channel. Of course, the late 70’s were the height of the receiver wars where each manufacturer was trying to outdo the other with more watts per channel and other features. This is probably why Onkyo decided to up the ante with the power output. Total harmonic distortion was lowered as well from 0.5% to 0.1%.
The late 70’s Onkyo receivers are very good performers and you be hard pressed to find someone that does not like them. They very regularly sell for quite a bit less then a comparable Pioneer or Yamaha receiver. So, for the money I would consider them sleepers and if you have a chance to pick one up cheaply you should do so.