If you just want 5.1, buy a 2nd hand yammy:
Yamaha DSP 3090 (original flagship 5.1 amp, I got rid of mine a couple of months ago). Still a class act even now, but no DTS.
£200-£250 (and this is a bloody bargain).
Yamaha DSP A1:
Like the 3090 but with DTS, and some more power
A brilliant amp, this is what I have now. Except to pay between £250-£400.
Yamaha DSP A2:
Like the A1, but with less power. I used to have one of these as well, a great amp, but sounds more strident at high volumes vs the A1.
£250-£300.
In short, flog your 2070 on ebay for about £100-£150 and go and buy one of the above 2nd hand. The difference is huge
PS: I still cannot understand why people buy cheaper amps with 6.1 etc. For the same money the performance you can get puts them all in the shade.
[not alot of software with discrete 6.1, although for TV pro-logic II is very good].