3W at 32 Ohms is plenty for almost any low impedance headphone. The HD600 and HD650 are both rated at 300 Ohms. At a 300 Ohm load an amp has to swing enough Vp-p to generate enough power at 300 Ohms to adequately drive the headphones.
I just turned on my calculator and looked at the HD650 spec sheet. Your amp would need to deliver 167 mW at 300 Ohms to get the HD650 to reach 120 dBSPL which many consider to be the threshold of pain. That is plenty loud. Check the spec sheet for your amp.
Generally, SS amps produce more power at lower impedances than high impedances. Generally, most high impedance headphones require far less power than low impedance headphones. My low impedance planar headphones work well with 1 W.