[pkasting]

I'm upgrading my Senn HD-580s (+ a venerable Oehlbachs cable) to HD-650s + a cable from Toxic Cables.
 
Currently I have an E-mu 0404 USB into a maxed-out PIMETA as my source + amp.  Wondering if I should consider upgrading the amp.  I'm into bang-for-the-buck, which I typically assume means either a DIY or DIY-from-a-head-fi'er amp design, in order to save the markup on a commercial amp, though I would be open to commercial amps that are competitive on price.
 
Would I see a noticeable difference from going to, say, an M³ or a β22?
 
Should I consider an amp with a fully-balanced configuration?  My E-mu does have balanced TRS outputs.  I haven't heard the difference between a balanced and an unbalanced setup.
 
And finally, is all of this doable for a reasonable cost?  I can't afford a $1000 amp.

 

[NA Blur]

It will probably be less expensive and more of a long term success to just upgrade your headphone away from the Sennheiser HD-XXX line.  Why not try an AKG K550, beyer Custom One Pro, or DT880.  Even the DT990 is better sounding to me than the HD-650 because it gives some low end oomph.

 

[Nanago]

Is the AKG 550 better than the HD 650?

 

[NA Blur]

The AKG K550 certainly sounds much less veiled and is easier to drive and easier to listen to with a wide range of music.  With that in mind I say yes.