I have a friend who owns a 403e. It is an excellent amp. High resolution, transparent and neutral without coloration. The downsides are the weight and cost. They are getting pretty old at this point and caps will be drying out. It may be in your interest to have Krell re-cap the amp if it starts getting glitchy. My friends amp had a channel start going in and out and hearing clicking sounds. These are likely the relays that don't have enough voltage to hold open because of electrolytic power capacitors drying out, lol. I have seen this problem in other older equipment.
That being said, you really have to replace that Emotiva DAC to something much better, such as LKS MH-DA005 or a Holo May or Audio-GD or something similar. The Emotiva XDA dac is not bad for the price, but it is definitely lacking when compared to others.