Hey guys, my local Firestone Audio reseller recently received the new 2013 models and after checking their website, I couldn't resist borrowing their new "Custom Cute" USB DAC and post impressions in here while I'm at it
Here's the official url: http://www.firestone-audio.com/fsa_firecute/fsa_firecute_customcute.html
I've never been too interested in "me too" products when after quite a lot of digging you can always manage to find innovating products that try to squeeze in the most proven-to-work current solutions and add "unseen before" features......and all this for a reasonable price.
New $1K DAC's are being constantly released, but the "Custom Cute" costs $299 and its SupplierHD PSU $189...That's a whole different story, especially if you have a cherished headamp and no use for a cheapish TPA6120 headamp in your DAC(or obsolete/technically inferior S/PDIF & AES-EBU inputs).
here are some internal pics of "Custom Cute":
You'll notice the XMOS chipset, that only requires drivers on Windows(they also come with ASIO 2.2 capabilities) and it's not fed by two low jitter clocks this time but by the same PLL1707 audio clock as in the Firestone Bravo transport that provides "perfect" zero PPM clock signals...talk about accuracy!
Then the I²S signal extracted from the XMOS chipset goes through an ISO7240M digital isolator that will provide galvanic isolation between the <XMOS computer side and the >WM8740 DAC side. I have yet to see this kind of design anywhere else, let alone for $299
Sure there are ADuM4160 isolators out there but these are capped to 12Mbit/s USB, I²S isolation would very much appear as the best solution to noise-free computer audio. If you have a noisy laptop, look no further the future of computer audio is here(and it doesn't cost 5 grand either ^^).
Then the isolated I²S signal is fed to the world acclaimed WM8740 DAC chip, that won this subjective shoot-out FWIW: http://www.audiodesignguide.com/DAC_final/DacFinal.html
Being a voltage output DAC chip, it does require a dual opamp for low-pass filtering but Firestone Audio played smart again and provided two swappable single opamps instead of a dual chip, so they both get their own dedicated power rail/caps and no need to bother with soldering tiny single SOIC8 opamps onto DIP8 adapters anymore...just roll the usual suspects(AD797, LT1028, OPA627) et voilà ))
It comes stock with two OPA604 opamps, that would apparently be notorious for being hard to please: http://www.head-fi.org/t/501046/the-lovely-cube-headphone-amp-lehmann-black-cube-linear-clone/975#post_8136795
Of course the SupplierHD linear regulated PSU and galvanic isolation both would very much apply as "best treatment" to me
I should also state that the XMOS chipset is USB powered(which is mandatory for galvanic isolation as both sides can't technically share the same PSU) so I tried my luck with a whole bunch of audiophile USB PSU's that only ended up making the sound muddy and unfocused....quite a surprise to me to say the least. Long story short, I guess Firestone do know how to properly filter the noisy computer 5V signal huh
Now, for the SupplierHD PSU: http://www.firestone-audio.com/fsa_firecute/fsa_firecute_supplierhd.html
It's always been a great idea to run the PSU within a separate faraday enclosure so EMI/RFI pollution onto the audio circuit will never be anything to worry about, it's great to see that Firestone kept up with this approach =)
I've made a few internal shots:
I can't tell much about it except that:
-the official link claims it to be an improved design over the previous Supplier PSU, providing two ±12.5V rails instead of a single ±24V
-it can simultaneously feed two FireCute serie units(the old one could only output 0.2A, the new one up to 0.6A)
-It comes with two mini-din DC power cables that are very stiff and appear strongly shielded, a far cry from the über-thin DC cables of the old Supplier PSU.
-there is a 110/220V jumper switch, which was not the case for the old Supplier PSU.
Here are some pictures of the CustomCute/SupplierHD combo:
My reseller's demo unit came as a Christmas special edition, but the regular version won't have any mention of this.......just "Custom Cute".
The DAC itself comes with a front switch to either use the SupplierHD PSU or the stock wallwart/old Supplier PSU. On the back of the unit, you only get the USB input, RCA output, SupplierHD PSU mini-din input and wallwart/Supplier DC barrel input.
So now that I gave a good overview of what's in the shiny boxes, time for me to fire up the combo by pluggin it to the line-input of my DP1:
2 minutes to install the XMOS drivers, setup foobar for ASIO et voilà.
Oh wow, Firestone's new sales pitch is the HD acronym.......well, they sure didn't lie
I can also hear why many ppl rave so much about WM8740 because it really does provide a highly enjoyable SQ, not as refined as AK4396/AD1955 of course....more like a nice in-between the "sterile/clinical/boring" sound and the lofi yet euphonic SQ of NOS DAC's for instance. I've never had too much interest in R2R because I couldn't locate any fairly priced DAC unit embedding them together with a serious USB input, but WM8740 certainly sounds excellent in this DAC.
The clean PSU, galvanic isolation and single opamps all pay in cash SQ-wise to my ears.....signal path is short, clean, SQ is uncompromising and the SS 3D'ness sounds as real as it's gonna get. I also didn't notice any harshness and I can only acclaim Firestone for putting together this HD sounding little unit. This kind of SQ for a bit less than $500 makes this combo a serious contender to feed a discrete/tube headamp I think, so you can benefit from a very clean DAC output and color it however you fancy afterwards.
I also had fun rolling opamps of course:
They both kind of tamed down the clarity of the stock OPA604 opamps but I wouldn't say that they sounded "better".......but more like less "focused" and more "relaxed", which might or might not be what you are looking for. OTOH, opamp rolling is meant to allow you to find the SQ color YOU want to hear in your rig.....so it will all depend on your headamp, the quality of your source files, your phone and more than anything else your personal taste. AD797 and OPA627 would be worth a try, too bad I didn't have any of them around
Edited by leeperry - 5/30/13 at 6:55pm