After trying it with help of my pal, I will report the result.
Amazing headphone amp at 50$
https://www.amazon.com/gp/product/B014FASL1A/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
1200×1200This is an amazing value at 50$.
I had been happy to drive HD 800S with Chord Dave direct.
Sound & Vision – 21 Jun 16Tube Amps for Pocket Change Nobsound NS-08ENobsound NS-08E Performance Features Ergonomics
I happened to come across above review.
Upon relying Amazon return policy, i pulled the trigger for it.
I did not expect any improvement by the amp.
It there is no significant deterioration vs direct Dave connection, it would have been nice.
On the contrary to my lower expectation, it made sound more exciting without harsh edge added.
https://www.amazon.com/Fairytales-Original-Master-Dogrobosz-Toneff/dp/B01D8QBNLM/ref=tmm_acd_swatch_0?_encoding=UTF8&qid=1573691594&sr=8-4
This is one of my favorite Jazz recording that I had enjoyed since 1999.
This CD sounds more natural with amp than through Dave direct.
Transparency got reduced by tiny bit but to tolerable extent.
It will work wonder for less Dac than Dave.
I am also going to do tube rolling with some Nos tubes.