AFFORDABLE (under $1K) Best SS and Tube Amps for HD600


Best SS Under $1K for HD600 (or similar load) __________________________________________________________

WHAMMY Class-A headphone amplifier w/ OPA2107 upgrade OR 2 OPA627 pro build ONLY $500-$600 PASS Design (similar to/ better than a dynalo- warm + clinical - choice of chip switches sound - these are two I like best- choices chips R infinite)
TCA HPA-1 ( Tom Christiansen Audio ) $899 (warm and clinical but not like WHAMMY

Gilmore Lite Mk1 or Mk2 (Like a Dynalo) $300-499 (nice- a bit warm/clear for SS)
Rupert Neve Designs RNHP $499 (clinical gain power)
neurochrome HP-1 Kit $500 (similar to DYNALO and TCA HPA-1)
Monolith by Monoprice THX AAA Balanced Headphone Amplifier featuring THX AAA 887 $399 (cheap and very good black velvet background- just nice warm sounding like WHAMMY or TCA or Gilmore)
Emotiva BasX A-100 Flex with jumpers activated for full headphone power $229 (gobs of raw power no real special sound except its fun to open the HD600 with this much raw power for cheap)


Best Tube Under $1K for HD600 (or similar load)
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Quicksilver headphone amp $899 (probably best looking of all these and sounding)
Bottlehead Crack w/speedball and upgraded power cord by them Professionally build ($800) (HD600+this is like peanut butter and jelly - everyone agrees this is nirvana for HD600)

TOR AUDIO Roger $560 (amazing like Crack without speedball/power cable) DIY Bottlehead Crack w/speedball $400+ 90 for cable + 8 hours time and no where same build as above
Bottlead Crackatwoa 800-$944 KIT ONLY qualifies here under $1K BUT you could get pro built for ($1700+)
Schitt Valhalla $349Schitt
Schitt Mjolnir $849
Woo WA3 Headphone Amplifier $599 (no longer made - find on used market or wait for ver2)Woo WA6 Version 2 $699
Woo Fireflies with DAC 2nd gen $999 Starving Student II Headphone Amplifier $229+ 8hrs buildTOR NICK Headphone Tube Amp $480 (wood w/tubes)
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Im probably missing a bunch but this is my short list! Please join in...
Honorable mention OVER $2500 probably no one EVER heard of: Toolshed Amps The Darling HEAD AMP made in USA $2595
128x128whatugot
Faced a similar dilemma recently and eventually went with the Drop   THX AAA 789.  I bought blind, but based on numerous reviews, it seemed to offer the best performance vs cost. I paired it up with a SMSL SU-8 DAC (everything balanced) and the results were spectacular.  It drives all my headphones including the Sennheiser HD650 (sibling of your HD600s) with ease and aplomb. 

I had a freaky experience a few nights back. I was home alone and playing something with lots of acoustic guitar via my Monolith M1060s and I kept hearing these rustling noises behind me. 

Eventually I determined it was just the guitarist's trailing fingers brushing the strings but the image was so holographic that it was coming from behind me to the left.

I've been racking my mind trying to remember the track but... The music was familiar, but this was the first time I'd listened to it via this rig.  

I haven't explored tubes in my desktop config yet, so I can't offer any feedback there. 

Mark
I just had the opportunity to compare Op amps in the Pass WHAMMY which I find sounds better than the crack/ speedball - really- no kidding.
Comparing the OPA627 (you need two so about $60) vs OPA2017 ($20)
Using the OPA627 is a bit more clearer and articulate across the spectrum - open spacious, clear and deep bass - like opening a window to the OPA2017

I if had just the OPA2017 in the WHAMMY - I already determined it sounds better than the Crack w/sb and the Emotiva Bas-X 100 - and the two MUSES8920 op amps in my TEAC UD-301. BUT - The OPA627 dual chip design is by far best especially in the WHAMMY. I have used many amps before this- and for a single ended amp this beats even the Bottlehead Mainline 1.1 and the Crackatwoa as well. The closest the Bottlehead comes is the crack w/sb and power cord upgrade but still not revealing the last details that the Whammy provides my HD600. I can not comment why the power cord on crack makes such a nice difference but it does-

I have rotated my ER-4 Micro Pro P and S editions in the WHAMMY and its a perfect match as well. Unlike the Crack or the Emotiva which pale when using these critical ear phones.

I also used the Sony MDR-V6 and MDR-2506 which usually sound terrible when things aren’t right- they are not the best for music long term though on any system.
I also used the Master Dynamic MW30 and they sound excellent with WHAMMY as well.

very impressed.
Caveat to WHAMMY- no output RCA and no front power on off switch, and you need to rely on a professional builder- I got mine from James the HeadAmpBuilder

I can not believe how good this PASS design is- I cant stop listening to music!
Just a thought, you could get a new pair of headphones for less than $1k which may make a bigger improvement. I would probably look at Focal Elex or some Beyerdynamic phones and then save for some better amp.
Nobsound NS-08E
https://www.soundandvision.com/content/tube-amps-pocket-change-nobsound-ns-08e
fitted with Nos RTC 5654 RT tube sound fantastic with HD 800s.

It cost me around 100 bucks including Nos tube and adapter.

https://www.amazon.com/gp/product/B078X85LFS/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

This combination of Nob and 800s sounds more natural and pleasing than Raal Sr1a driven by Jot R while the latter sounds more open and exciting but close to hot.

This one also may work well HD600.