Need Help on HeadPhone AMP

OK, tired of bickering with the wife about playing the rig too loud. bla bla

My rig is as follows:
Channel Island mono block class d (d200)200 watts
Acoustic Research LS-8 pre-amp
Rotel cd player (used as transport only)
PS Audio digital III DAC
Acoustic Zen Adagio speakers
Creek OBH-11 headphone amp
Grado SR225 Cans
Soundstring interconnects
Kimber Silver Streak interconnects

At this point the Creek and the Grado are just not cutting it for me. so...... your assistance please

I would like to replace the grado and creek and keep it under 2500. Suggestions?

Sennheiser Cans? Better Grados? I'm not sure of the amp at all....... THANKS so much in advance