Verry good decision. After that you will know what high end headphone sound can do for you. If i may act as a prophet this might be the beginning of a collector’s career:)

The difference 009 to 009s is not that big. But I prefer the new model in the high frequency. I don’t think dynamics and magnetostats offer anything really superiour to an excellent E-stat rig, but can offer more bass impact.

The BHSE is still commercialy available at headamp.com and a really great amplifier dot it is the best Stax amplifier I ever owned, and I had a lot of them. It sounds excellent with every Stax phone I plugged in. The Cabon is only a different flavor. The T2 is supposed to be superior but not...

If you ask this quite general questen and want to spend the amount HE1 is the right answer. If you start studying deeper there are many alternatives. EG go Stax route (MSB Dac > Diy T2 > SR-009S) or Ortho : MSB > Pass 150 > Hifiman Susvara

The frame of the Signature will be dark brown vs black with the Lambda Pro.

There is a guy in Germany who does the CCS mod on those T1/006/600 and even 007t. He is verry professional. http://stritt-audio.de/stax-driver-units/ The site is in German, but he speaks reasonable English. Brings those Stax amps closer to the KGST.

@ericj https://www.electromod.co.uk/stax/cables/cord-assembly-sr-001-002-stax/

well sounds like a SR-009 just with a marvelous black background

You can allways buy a replacement cable ffor example here https://www.electromod.co.uk/stax/cables/

After owning the A8 for 4 years and nearly every Flagship headphone out there I feel quite sure to rate them, starting from best  (surly forgotten some I had). All the listed    Stax 4070/BHSE > Stax 009 and 007 MK1/BHSE > Hifiman HE-6 /Accuphase pro 3 > Stax SR-407 /313>HD800/Bryston BHA1>...

My BHSE is Birgir made and it should even sound better than the headamp due to the PSU closer to the amp and better parts.

I have listened to the Solaris extensively. While it was spectacular withe the HE-6 (for me best sound of show) and definatly better than the Luminare the prototype sill falls short of my BHSE or KGSSHv. The bandwith is still too small to take a fight with the heavyweights when you go up with...

I have heared quite a number of 007 and even among MK1s there is variation (roughly said carbon box ones are more neutral SN<705xx) the best is my actual one a verry early SN701xx. But the new one I heard was really good too, a bit more exciting sound as my neutral reference one. So I agree...

This will be far more than my wallet can swallow

Quite normal outcome as the standard meter has an impedance (~6MOhm in this case) that is too low compared to the Output resistor. You build a voltage divider with the meter and the protection resistor. To be sure measure with an Voltmeter with >100MOhm or simply before the 4.7M resistor.