I recently replaced my almost-never-used Sennheiser HD 600 with a pair of Focal Elear when retailers were clearing them out cheap last fall because of a Focal model change. I love them. Clarity, detail, dynamic punch, comfort.
Now I need to find a good home for the Sennheisers.
I added a Decware ZROCK2 to my headphone only system last week and it really cemented my love of the combo of ZMF Ori and PS Audio GCHA. The ZROCK2 allows me to add just a bit of EQ that really fills out the soundstage and gives a bit of bass impact. There is so much clarity with this combo that I have to remind myself to turn them down a notch or two. . . .
On my desktop: I started with Sennheiser HD-600 and a basic Schiit stack with Wyrd. A very good start. Then, I acquired Hifiman Sundara and I use it with my new desktop toy – the Stellar Gain Cell DAC/Preamp. Yep. Try this sometime – iMac/Roon/USB into the Stellar, then XLR into **powered, near field monitors – the Neumann KH120A’**s on isoAcoustics stands. Awesome set up. My Neumann’s sound as good as my HD600’s, which I would never have dreamed. Flat, accurate, revealing, imaging/soundstage crazy good, and listenable. “Passive bookshelf speakers” were an expensive rabbit hole/diversion for me. If you can’t afford the KH120A’s, try a pair of Tannoy Gold 7’s at half the price. Dual Concentric desktop bliss.
On my primary all-PSA system, I use Focal Elears into my PSA BHK Preamp. But I prefer my Tannoy Cheviots.
Wow, that’s an interesting setup. Thanks hoytamundo!
The Stellar Gain Cell DAC built in HA is decent as well.
I love it! I was spoiled at the office because I was able to listen to it with Tidal all day. I use a Sprout here at the home office which is quite good. BHK pre headphone amp still knocks it out of the park when I do some late night listening.
My vintage balanced AKG K1000 still sing well. They designed them for a class A MOSFET headphone amp. Alternatively, they could be connected to speaker terminals behind the power amp 
For Audeze LCD-2, would I be better off using a modern Schiit Jotunheim or an old Rudistor RPX-33?
The Rudistor is dual-mono, class A with oversized toroidal transformers and very high quality tight-tolerance components, and outputs 700mW. Hand-crafted in Italy.
Single-ended, though.
The Jotunheim is balanced and does have quite a bit more power, but its insides obviously look flimsy when compared to the Rudistor. And I trust they are flimsy too, just well-engineered.
How much has the science of building headphone amps really evolved since 2006? Can a well-engineered cost-efficient design of today outclass a hand-crafted dual-mono class A marvel from times past?
I’m leaning towards the Rudistor…
I would say, way better than decent.
I have been pretty shocked how good the Stellar GC head amp is. (Sennheiser HD600s and HiFiMan Sundara’s.)
I have become an evangelist for “powered near-field monitors” that audio pro’s use to mix on. Neumann’s, Tannoy’s are two that I can absolutely vouch for. But there are many brands I have never heard of that are highly regarded – Adam Audio. Check out Sweetwater.com. These monitors are all XLR (nice with the Stellar DAC), tunable in HF/LF and with front ports, are very easy to position (if you use isoAcoustics stands).
I have several headphone amps. The Stellar Gain Cell DAC HA does a good job. Not as refining as a premium dedicated headphone amp, but I never expected it to be. It doesn’t disappoint.