Suggestions for pure headphone amp around $200?


I am looking for suggestions for a new to me headphone amp with a budget around $200, maybe a little more for the right unit.
I do NOT need a headphone/dac, it will be fed by RCA analog from the line out of my BAT integrated.
One requirement is that it also has RCA analog outputs, so a pass through if you like, my present el cheapo Monolith head amp has this and it is near essential in my set up right now.
My present cans are HiFiman 4xx purchased from Drop.
I may be looking at better cans for Xmas so there is that to bear in mind for the new head amp.
Thanks and stay safe!
128x128uberwaltz
Post removed 
I looked at the Aune X7. At 11 ohms output it is only suitable for high impedance cans.
The Drop is not available for at least 8 months.
They are suspect anyway. When the sold Grados, the Grado company said they didn’t front them any.
Where the hell did they get ’em?
Much stuff NO warranty.
The S.M.S.L. amp I have doesn't sound as good as either Schiit I am using.
It has been suggested, probably rightly so, that I really need to increase my budget a fair bit and more " future" proof my purchase of a head amp.
Check into the Valhalla model. Reasonably Priced. Feature Packed.
Description, Spec, And FAQ all contain useful information.
OTL, Pre Output, Rollable, and adjustable Gain. 
Separates / Component Type Use.
Schiit says: "Valhalla 2 is exceptionally accurate, neutral, and resolving, without being strident or etched. "
My V2 sounds as good as the Mjolnir. A little more expense ($350 new).


Look at Schiit I don’t know off the top of my head but they do have a headphone amp that is the same class A circuit as their Aegir amp. I think the Aegir sounds great and would expect the headphone amp to be on par.