After some very pleasant interludes by the member above, I have a small adjunct to the module archive, which is a comparison of the old (200x - 2007) wallwart with the new wall wart that is gradually rolling out on an 'as needed' basis in the Desktop line. I have no details as yet on when, if ever, the low end Desktop and Micro Amps will come with this PSU as standard.
Basics:
The old 'brick' is a simple linear regulated PSU, with a maximum current output of 240mA per rail. The new 'brick' is a larger, switching PSU, with a maximum current output of well over 1A per rail. The original PSU is set to a specific input voltage, whereas the new switcher is universal. The new switcher is a fair bit larger and heavier than the brick - something to be considered for those wanting to take two with them along with a Micro Stack.
Conventional PSU wisdom suggests that, within its current limitations, the old linear regulated PSU will be better than the new switcher, but as always with audio electronics, knowing the technology at the heart of a design does not tell you for certain how well it will actually sound in a given circuit/system.
My first comparison is with Max '06 Modules, using analogue inputs. In this configuration, the power consumption is getting towards the top end of the 'brick' output, but still within it. Headphones are HD 650's, with stock cable. I can't imagine anyone will have this configuration, as I would assume anyone with Max Modules will have a DPS, but it makes a good comparison at the upper limit of the old PSU.
This isn't a subtle difference in this config. Switching back and forth between the two, there seems to be reduced channel seperation and rolled off frequency extremes with the old brick, as well as slow and muddy bass. The new switcher seems to improve on all of these issues - the top end opens up significantly, and the bass is definitely cleaner. The high end is the most major area of improvement, where ambient details in the high harmonics fall into place where they seem to be simply absent with the old PSU. The switcher might err a hair too far in that direction, with the sound at least from my first impressions being slightly edgy where the old one was rolled off. Even with that caveat, given the choice, I'd go for the new PSU in this instance.
As a final test, running the amp at high gain with no source, and the volume control set to maximum yields a slightly lower noise floor with the new supply.
This is a worst case scenario for the old supply, as it is at the top of its ouptut range and has little or no dynamic headroom available. The next installment will deal with an 'absolute quality' situation, where the old PSU will be operating well within its output capability.
