I have been offered a Yamaha DSP A1 for free. Firstly is the unit any good? Secondly I intend to run my Naim SBL's with a Naim nap 150 off the main channel, however I now need 5.1 speakers for the other channels. Any suggestions on what speakers I can use that won't sound dreadful compared with the SBL's but at a reasonably cheap price