Well, they're some hours past the 150hours and I can say if you like your stock HF2 (which I do/did) you'll be overwhelmed by the difference with the Vixen.
However, still not doing a review because I decided to see what they're like with BlackMax cabling instead of my pair that have BlackCopper - so have ordered another pair to be done (Black Palm wood, and BlackMax). I can state, however, that there two huge changes IMO - whereas I'd call the stock bass as adequate with bowls - there is now more, and the "soundstage" has gotten very much larger. I put on RS-1/flats last night as part of another kind of comparison and found if you A/B the two 'phones - it makes the stage of the RS-1 seem shockingly tiny. But, I'm still going to retain my RS-1's ........there is always room for my old RS-1/flats, Vixen HF2, and X-Deep 600ohm Darths . Will say, as daily choices I'm seeing - when closed is needed = X-Deep 600ohm, otherwise Vixen HF2 as the primary choice for open. I like these Vixens - but, no real review until the Blk Palm/BlkMax pair arrive and get a decent listening (but, the HF-2 being sent for "destruction" have burned-in drivers).
I like to wear them with a loose seal (as I also do with Darths). Also went a step further toward opening things up by piercing the velour pads with a leather awl all around - don't know if it made any real difference, but it can't hurt.
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