[willkayak4food]

After my recent troubles with the otherwise pretty nice sounding HiFiMan EF2A, though I'm not entirely ruling out giving a replacement EF2A a chance, I feel I should be keeping my ears open for something else to take its place, as I'm now a bit wary of HiFiMan's quality control issues.
 
In general, I love the sound of tubes, and if well implemented, they do seem to alleviate some of the "congestion" I sometimes feel with headphones (even though I truly enjoy my "open" HD600 phones - with the wrong amplification, even they can feel a bit claustrophobic to me).
 
So then, this potential new DAC/amp should be able to make my Sennheiser HD600 phones sing, and my heart leap (or is the latter simply asking too much? ).
 
Though I obviously do care about the sound, headphone listening is something I do only when I really need to (when away from home and speakers), so I'm not looking to "break the bank" in the collection of headphone gear.  It would be great if I could find something for $200 USD or less, but if something is truly spectacular, I may consider spending up to around $300 USD.  I'm happy to purchase used gear in great shape, thereby perhaps getting a bit more bang for my buck, considering the just mentioned preferred budget.  Either way--new or used--I'd love to know about some very nice sounding portable tube DAC/amps.
 
Thanks!
 
PS: My Audioengine D1 (w/DAC) has analog outputs, so if an appropriate "amp only" solution is found (provided it has a pair of analog RCA inputs), I would consider that as well.  It's just that I really like the idea of a small, combined DAC/amp for greatest convenience/portability.

 

[tzjin]

The BottleHead Crack will make your heart sing... if you DIY and spend $275 on the kit. They do sell it assembled for a little bit more.

EDIT: I missed the portable.

It's my understanding that the Alo Continental is one of the best portable tube amps you can get, but it seems to be out of your price range. There is a clone by Fanmusic that some say sounds just as good on the auction site, but it's risky.
 
Somebody was selling a TTVJ Millet Tube in the FS section just a little while back for under $300. He was also selling the TTVJ Amp/DAC which is supposed to have a very tube-like sound, for the same price.