Currently i own k501 for a month and sr225 for 1wk. To tell you the truth, I like both phones. They're like odd couple, but so far it works.
After 1 month of hard listening, k501 are excellent cans for classical and jazz.
Their strength are:
sweet midrange, wide soundstage, silky smooth delievery, amazing instructmental separation, non-fatigue sound, super comfortable, beautiful fit and finish, and delicate detail.
Their weakness are:
limited low bass extension, grainy high during heavier bass demand, unforgiving to recording, sensitive to amp/source, vague in center-imaging, lacks vertical depth, and not adaptive to certain music.
If match right with recording, amp and source, k501 will shine and deliever.
It took me while to figure this one out, but now I'm happy with them.
You should check if k501 will go fine with your set-up. I can't answer since I don't have your amps nor tried one.