The DB9 amp from DB Systems sounds surprisingly close to the Perreaux but the build quality is more than a little distracting. It is a real lightweight, performance aside, with it's hard-wired wall wart and it's cheesy "enclosure". I must tip my hat to Dave Hadaway for the performance of this diminutive little amp but at the $235 msrp, or even at the $149 AA sale price, it's over priced. I wouldn't expect to pay more than $100 for it.
The Perreaux on the other hand is built like a tank and well worth the $350 (I got mine for $299 at AA). I was more than a little impressed to find test plots for freq. response and noise floor for my serial number device. And the numbers are near perfection; a true 1.0 transfer function. But as nice as this amp is, and believe me I like it a lot, if I was to blind A/B it against the DB9, I think I would be hard pressed to tell a large difference. At least it wouldn't necessarily be a slam dunk. But the Perreaux in build quality, power supply, aesthetics, etc. is worth the extra bucks. The DB9 will be going back to AA thanks to their 30 day return policy.
I also bought a pr. of Senn HD600s for a net cost of $200 after sale price AND factory rebate. This has been the first time I've heard them and must admit that they are something special. They are easier to listen to than my old MDR-V6's. However, if a guy/gal wanted to get max bang for his/her buck, buy the V6's (seen them on the net for $69) and the little DB9 for $149, they would be hard pressed to find that level of sonics for the $218 invested with other combinations.
The 600's seem tight on the sides of my head and am hoping that relaxes a bit after more wear time. And by the way, if you want to push the low end of your headphones, speakers or your listening room, check out Bela Fleck and "The Flight of the Cosmic Hippo". Victor Wooten's bass on the title track has been known to rearrange furniture. For further bottom end adventures have a listen to "That's the Way Love Goes" on Norman Brown's After the Storm.