Headphone tube-amp with oddball OPT

[obsoletemac]

Hello.
I've been playing with the idea of building a tube/valve headphone amplifier for a couple of years. The first idea was to make some OTL-thing, probably with some really big bottles, like 6AS7, so I bought a pair of 600Ω "AKG K240 Monitor".
For various reasons, this little project was put on hold, but recently I've been thinking about again, but this time with a little OPT.

The intended OPT, called CTX01-13660 from Coiltronics (don't bother trying to find any datasheet, it's likely a custom design), is intended for power conversion. It's got a primary with a center tap and single secondary. I've done some measurments using a HP204D from 10kHz to 500kHz (sine wave) on the secondary measuring with a Tek 2246 on the primary. There appears to be a 5.7 turns-ratio, pretty constant below 60 kHz.
The core-size and "look" is nearly identical with Coiltronics' VP2, and estimating maximum power capability from their (available) datasheets would suggest that it could be capable of about 4W@100kHz. 200mW (the power limit for K240 Monitor) should be within their limit in the audio range.
(pretty vague, huh?)
Now, why would I want to use that with tubes and headphones? Well, three(hundred) reasons:
1) I'm curious
2) Haven't seen it done
3) A reel with 300 of them sitting on a shelf gathering dust

I found this http://www.freewebs.com/valvewizard1/pp.html [1] and started drawing load lines for full class A and 20+ double triodes, triode-pentodes and pentodes in my collection that I had in large enough quantities to make a stereo amp.
I finally ended up with PCL200. (See attached image)

My calculations so far:
With turns ratio of 5.7, reflected impedance is 19500Ω, half of which is seen by each tube, i.e. 9750Ω

The maximum input power for K240 Monitor is 200mW, which translates into a voltage-swing of 11V (RMS), or 31V peak-to-peak, if I've calculated correctly.
This should mean that the required anode AC swing for each tube is 176.7V, rounded to 180V. I marked the Ia and Ua limits with red lines and selected Ub (ignoring any DC resistance in the OPT) to 130V, marked this with an orange line. I also marked the required 180V swing centered around Ub.
Following [1] I drew the green load line, and transferred it to a suitable working point (blue line).

The working point seems well suited for LED bias, and the entire power-stage seems very sensitive.

So, now for the big question. Does it make sense at all? Are my calculations correct(ish) and does it seem to be a possible solution? If that is the case, I'll be able to move on to the next big question: CCS-loaded LTP or Cathodyne…

[IMG]www.bjelle.se/PCL200-pentode-with-load-lines.png[/IMG]