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
Following on the Darko reviews I’ll suggest the DROP + THX AAA™ 789 Linear Amp.  Yeah, it’s $299, but you said “maybe a little more” and what’s 100 bucks among audiophiles?  The review puts this unit in another league from the very good Asgard 3, so for only $100 more I know what I’d do.  And given its ability to scale with better gear it covers you more for when you upgrade your ‘phones.  Just my $0.02 FWIW, and best of luck in your search. 
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.