Advice on running HD600's through a M-Audio ProFire 610 vs a budget amp

I just got a pair of HD600's for the first time.  I used to own many Grado's (usually ran un-amped) and departed headphones for a while for speakers.  I recently acquired the Senn's in getting back into headphones after a hiatus (forgot what I was missing).  I think the HD600's were the headphone for me all along, I just never gave them a try.

I currently only have a M-Audio ProFire 610 interface.  The HD600's sounded good but weak out of my iphone/macbook but they came alive and were pretty full and amazing out of the 610 with the volume near max.  I am wondering if a moderately priced dedicated amp around $200 used would be a worthwhile upgrade or if the 610 is going to be on par with anything in that range.

I was specifically interested in the RSA Hornet as a portable, but really just want to be able to take the headphones around the house and to different spaces.  So 610 vs RSA Hornet vs other ~$200 option vs just wait and save  

These are the 610 specs:

Headphone Outputs at Maximum Volume into 32 ohm Load
Frequency Response	+/- 0.1dB, 20Hz to 22kHz
Signal-to-Noise Ratio	-108dB (A-weighted)
Dynamic Range	108dB (A-weighted)
THD+Noise	0.003% (-90.0dB), 1kHz, -1dBFS
Max Output Level into 32 ohms	+2.9dBV, typical
Power into Ohms	60 mW into 32 ohms
Output Impedance	75 ohm
Load Impedance	24 to 600 ohms
Crosstalk	<-75dB @ 1kHz

Not sure if this is the relevant measurement, but in M-Audio forum I read the following differences in specs:

ProFire 410 Max Output Level into 32 ohms - 3.5 dBV, Signal-to-Noise Ratio -101 dB  

ProFire 610 Max Output Level into 32 ohms +2.9 dBV, Signal-to-Noise Ratio -108 dB

I guess if nothing else, it appears they are not exactly the same.  I can say there is a big improvement in the 610 compared to the headphone out on my MacBook (sound gets bigger, tighter, and with a little sizzle).  I suppose this is just wetting my whistle, I have no concept of what the 600's can do.  I might pick up a used amp and see if I think its worth it or not.  I record with the 610 so its always useful as a DAC.