> So I've been reading about amps a lot and for the longest time I was really really drawn to the Benchmark AHB2 amp. Mainly because I happen to be a pretty measurement focused buyer.
I can hardly believe my eyes! Are you serious in making purchase decisions based largely on measurements? Are you not more concerned about how they actually sound? It's a bit like saying “I choose the concerts I go to based on the measured acoustics of the venue rather than the performance itself”!
Sorry, but I must get this off my chest first! OK I've calmed down so let's look at your next point:
> Now that I've been reading about how far class D amps have come its got me into a spot of confliction. While I realize I could easily go the DIY route with the Purifi or Hypex, I want something that has a nice enclosure like the Benchmark.
The "DIY route" entails the purchase of a cheap off-the-shelf evaluation board and adding your own power supply, case, etc, etc. This will offer an indication of what Class D may deliver, but nothing like the result of the Class D system offered by the likes of NAD or T&A. They build the Purifi Eigentakt Class D amp (the best Class D technology currently available) under license using superior components and get the whole box of tricks working as a unit that will rival any other SS amp of any class - a far cry (sorry to say this) from either DIY jobs done by you or I, or even from one-man bands who set up shop (probably in their spare room or garage) to knock up "Purifi amps" that they sell seemingly cheaply on Ebay etc. You just won't get the pro-products that well-established and respected brands offer – with warranties, customer support and anticipated good re-sale price when you next upgrade.
And Benchmark! OK, have you home tested this amp in your own system? If you do, and you also get into your system a handful of other good amps, you are unlikely (I predict) to purchase the Benchmark - or like me, you are convinced by its wonderful measurements and generally favourable reviews to buy it untried. I did this on the rave recommendation of a fellow forum poster who had almost identical speakers to mine. I found lots of lovely features (adjustable gain, exceptionally low noise, nice case, etc), but ended up with a drearily DULL amplifier. The Benchmark offers no sparkle, no goosebump factor, no real feeling of sharing your room with the artist, no temptation to turn up the volume! No, you sadly get little more excitement than "elevator music". Great for background sound while you are doing something more pressing than listening to music, but in a word - dull.
The only way to select a good amplifier that suits your room, your speakers and you music preferences is to select 6-10 amps (after reading reviews, recommendations, etc) and buy (used) or borrow these short-listed amps from dealers. Reject the dull ones (likely including the Benchmark) and carefully listen to the best of the batch before making a purchase decision. Let you ears be the deciding factor, not what some reviewer has suggested and not for goodness sake, what the oscilloscope says!
Sorry, but I’m saying this from first-hand experience that I hope you can avoid. I wish I had loved the sound of the Benchmark – it would have saved me a couple of years of experimentation with 12 solid state amps that I hoped would provide equally good or better sound than my previous SET tube amps, but in the end I bought a bargain Class D amp from a weel respected brand that knocks spots off the Benchmark and many other amps of Class A and AB designs. Good luck in your search.