[Doorbell]

I love the sound from this little dac/amp but I can't help but wonder about better digital audio.
 
Should I buy the E09K to connect with the E17? Or should I just buy else? What would you recommend? My current main headphones are Audio Techinca M50x and Grado SR80e. My budget is $200.

 

[PurpleAngel]

I would say to keep using the E17 and put all your audio budget for new headphones.
Sell off one or both of your current headphones and put the cash towards new headphones.
Maybe Audio Technica headphone, they are low impedance and it's very easy for the E17 to drive them.
Might find a good deal on used Hifiman HE400s