Here's a semi-hypothetical: if you had to choose only 1 combo, what would you rather have, a well driven 007 Mk2 ( not Mk1, just because the Mk2 is the current production and more readily available, and driven by a KGSSHV or BHSE) or a 009 with a mid-tier amp (for all available e-stat headphones, that is) , something like the 323s, Woo GES, srm-007. If you get either headphone from PJ then I think the prices are similar (1800 + 2500-5600 = 4300- 7400 for 007 setup, and 3800 + 700- 2000= 4500-5800).
Only thing I haven't heard in that list is the GES, I'd take a Balanced Dynahi + HD800 over any of those. The 009's are easy to drive but if your goal is spend cheap on amplification say a 323S which drives the 009 just fine but lacking in areas when you move up to a KGSSHV or so with the 009's you may as well not buy the 009's but this is if you plan on keeping the cheap amp as a permanent solution. I'd think you have to pay more attention to your source for the 009 than amplification due to the neutral bright tonality. O2 MK2 I found has too much boom and bloom with the mids and is uncalled for on some genres that have just a tad bit of mid bass going on. Now I've only heard the MK2 once at my dealer and completely far apart to the first time I heard the MK1's so I'm not so sure if the MK2 are as hard to drive properly as the MK1's.