Which ARC reference component to upgrade?

Hi, have you tried driving you Ref 110 direct from your Dac , eliminate the line stage. I owned a Ref 110 and found it to be a bit overated. The Ref 110 only sings with easy loads as I think the output transformers are too small and easilly saturate. The result for me was the bass , although it would go deep it was some what slow and loose. Selecting the 4 ohm tap improved matters in the bottom end ,but dynamics then suffered. selecting the the 8 ohm tap restored dynamics at the loss in Bass definition. Please don't get me wrong , the Ref 110 was musical but didn't rock my boat. Your speakers dip below 4 ohms at 220 hz , see Stereophie measurements of your speakers. I believe the Ref 150 improved matters. My amplificatin is now VAC , this gave me what I was looking for as my speaker dip to 3 ohms in the bass. I don't expect you to buy VAC as I did although you could try it for yourself, the Ref 150 could be a good place to start, only my opinion.