I have an IDA-8 and have made several mods and upgrades to it. I will list each one and the improvement it made (of course IMO). Speakers are Golden Ear Aon 3.
First, Bob at TDSS did his upgrade and that made a 175% improvement. Everything is just better.
Next was a Cullen Cable Crossover power cable - requires ~75 hrs break in - 30% improvement - sounds more powerful, like it added 15-20 watts.
Next was Synergistic Research Black fuse - 35% improvement - blacker background, better edges on instruments, more dynamic, more accurate tones.
The difficult thing I had with the upgrades was how much money to spend on a $999 integrated amplifier. With the progress I have made on improved sound quality, I have come to the conclusion that the IDA-8 is on par more with a $1999 integrated. Any cable changes I try are significant, indicating to me that the quality of internal components are indeed capable of demonstrating differences. In comparison with a standard consumer receiver from a local big box store, tweaks and cable changes barely make any audible difference.