I bought the A&K SR15 Norma with intention of selling the Pioneer XDP-300R, and ummm I ended up keeping both and using both equally. 300R sound is better to me... wider, cleaner, more airy. SR15 is more intimate and warm. Both are great for sensitive IEMs (I use Campfire Solaris). So, now I'm in your boat, except I have two devices that need a single upgrade.