I am looking to upgrade my amp. I currently have a cambridge audio A1 which i picked up for next to nothing. I think its letting my system down. I have a Pro-Ject Debut Carbon with the Ortfon 2M Red cartridge, Nad PP1 Pre-amp, Mission 771 speakers.Does anyone recomend any decent amps which would suit my system for under £150 (I have a low budjet) I assume something secondhand and older which be more value for money? Any help would be appreciated.