Some really good information in the impressions rolling in. Here are some helpful tips: - if you hear flabby bass or too boosted mid bass, you are feeding it too high of an output impedance output. Try a low impedance (under 1 ohm) source, to hear the bass as designed. It’s deep/sub bass titled. Even 2 ohm sources impact this. - if you hear grain or slightly harsh highs, try for deeper fit. The treble was tuned for near reference plane fit. Try a smaller size tip than normal to fit deeper or try dual and triple flange tips. Deeper fit will produce a smoother treble but maintain plenty of sparkle. - with proper depth of fit and a low output impedance source, the Plus should sound like a slightly warmer but clearer, more resolving and full bodied ER4XR.