Definition DC8 is an awesome speaker; top 5 value among all commercial speakers, imo. I almost bought a pair and might still. Coax and low order filters makes a very natural, open and alive presence. VERY accurate tone and dynamics. If you are willing give it the electronics it deserves then you will have a very high value speaker, with performance far beyond its cost. I've not heard the other Definition models.
I own the DC8s, still trying to find the best match for them...I demo-ed them till now with Hegel H190, Nuprime STA9+Dac9 and Primaluna Dialogue Premium HP+Chord Qutest. Last one sounded by far the best till now. It lacks precision when it comes to complex and punchy music.
On my list to be tested I have the ECI6, Aw100, Naim Unity Nova and Yba A200.
Any recommendation is warmly welcomed.