Suggestions for pure headphone amp around $200?

Just an update.
I did find a package deal that was an excellent price so went with it.

Beyerdynamic A20 head amp matched with Beyerdynamic T90 cans, both designed to work together and the cans are 250ohm.

First play was last night and a world of difference from my old setup.
A lot clearer and pinpoint imaging, bass although maybe not quite as deep was much clearer and tunefull whereas old rig was more thud, thud on the bass.

For the money I am very happy, a hair more than $200 for the head amp if I split the prices up but way less than $300 so I got what I was looking for.
Many thanks for all the kind suggestions along the way!

Really grown to like and appreciate the strengths of the Beyer combo.
While bass is not ear pounding, it is tight and tuneful and plentiful.
Imaging is glorious and mids and highs are sharp and very well detailed.

Obviously still lower rung stuff compared to what some people have for headphone setups but quite a way elevated from my previous setup.

The Dark Voice 336se is a nice tube headphone amp that can also be used as a preamp , priced in the $250 area.

I like my Schiit Asgard 3 headphone amp with upgraded power cord. I drive a pair of HD650s. It’s got RCA out as well. 

Yeah, me too.  I know that the OP has made his purchase, but for those looking for ideas, The Schiit Asgard 3 is a great option for not a crazy amount of money.  I've got a few pairs of headphones, including the HIfiman Drop 5XX, and the Asgard allows such a gorgeous sound stage, wide and with distinct instrument placement.

I had the Schiit Vali 2 before and it's a great option as well, but the Asgard 3 allows more detail, and doesn't have the huge wall wart.  In fact, I bought the Asgard 2 on clearance because the Asgard 3 was so impressive.  The 2 is warmer sounding which gives a different option, depending on my mood.