From my experience an used ENGL could be found very cheap. We are talking around 500 Eur for powerball2/fireball2 and around 600 for blackmore. I can vouch that fireball60 or engl savage have very good master volume and sound very good at very low volume. And they do have very very solid cleans. If you are going with new amp and MT15 I would suggest using JHS Little Black Box. Its passive master volume that you put in the loop and will help with MT15 volume tapper issue. Its 44 eur in Thomann.