What should I do

I understand how you love your speakers so what I'd recommend is getting a Marantz PM-15S2b (the limited edition) and use it's headphone out for whatever headphones you get and still have it for your speakers.

All the best,
Nonoise

Condo or not, play it loud!

If you love Harbeths, I have a hard time believing you'll like the HD800, at least not without over-the-top warm tubes. Have you heard them? I heard them a while ago, and was not impressed (poor Qualia 010 ripoff). The HD650 or HD600 are both excellent, cheaper, and may be more along the lines of your Harbeth's sonics.

Also note that while Rogue tube amps are great, their built-in headphone jacks will not compare to a decent standalone headphone amp, or integrateds with a reputation for good headphone jacks.

You may want to look at a Manley 300b based preamp, which is also a state of the art headphone amplifier, it is one of the world's most remarkable preamps and I think you would find it to outperform the Gamut preamp, and then you can have your cake and eat it to, on some of the headphone forums this combination of preamp/headphone amp and the HD 800's has been lauded as one of the most synergistic and satisfying setups there are PM me for more details.

Mulveling's post really hits the nail on the head and I say this based on experience with equipment mentioned in post(s). I appreciate those who show respect for their neighbors rather than the common me me me behaviors that have become the norm in many places. Thank you for your civility which is becoming something of a rarity in so many areas of western life.