The Tact's A/D and D/A board get a LOT better after Aberdeen Components modifies them. My XP has all the mods Aberdeen offers, including power supply, motherboard, A/D boards, and D/A boards. They put the XP in a totally different class vs. stock. To note, with the XP you dont have to use a computer - everyhting is done inside the unit - although you can use a computer, and you will want eventually if you want to fine tune your settings.....