Amber,
1. Having tried them I and others have found that batteries are not the best for sound quality. Of course I accept that there are many types of battery but for instance with my Qutest the battery was beaten fair and square by a good LPS.
2. No, LPS do not ‘pump out a lot of RFI’. I think it has been suggested that the transformers used in LPS do little to isolate mains rfi from the device but that is a different matter and in any case does not seem to be an issue in real terms, at least not with the LPS that I use.
3. Rob did a lot of choosing to select the best smps with each device but I and many other people are not easily parted with our money and yet we are prepared to spend significant amounts of it having heard the very real sound quality improvements by using a top quality LPS. MInd you I can only speak for the Mscaler, Qutest and Dave because those are what I have owned and used (and still use) with an after market LPS. When I owned the TT2 I always used it with the supplied smps but only because I never got around to trying it with an LPS due to its short period of ownership.
I am sorry but I am going to completely disagree with you over this one.
A little background to this; just as Covid started I wanted to design the best possible RF filter using SPICE simulation. I modelled PCB traces, internal parasitic capacitance, resistance and inductance to all the filter components, and set myself the target of eliminating RF noise from 100kHz to 10GHz - the areas that we have subjective problems with. I then set the task of making the RF noise OP to be sub 10 pico volts, using typical measured levels of RF noise as the input. Firstly I used a switcher voltage - indicative of the noise from a quality switched mode PSU. This was extremely easy to eliminate the switching noise - just a simple 3 stage RF filter, something I fit in all of my designs. But the real issue became when I replaced the input with a typical switcher voltage to one of random RF noise. And to eliminate that was a complete nightmare - it ended up being a very complex design, as it's almost impossible to remove random RF noise down to pico volt levels.
Why the issue of random noise? The problem is noise floor modulation, and this is caused by any non-linearity in the signal path with
random RF noise, as this creates intermodulation distortion, the products of which is random with a white noise spectrum from DC to 10GHz - but it's the audio component to this that gives you the noise floor modulation. But if you use a switching component only, this creates discrete frequencies which are outside the audio bandwidth, so are not directly audible - so switching RF noise is easy to filter, and has a smaller subjective consequence too as it does not add to noise floor modulation at all.
And noise floor modulation is very, very audible - my recent research and listening tests indicates that even noise floor modulation as low as -350dB is perceivable under single blind conditions. Which basically means any noise floor modulation, no matter how small, will change your perception of timbre. Adding noise floor modulation makes it sound brighter with an entirely artificial sense of transparency, which may sound impressive on an AB listening test but will damage musicality (as timbre variation is suppressed) and increase listening fatigue.
Audiophile linear PSUs have no RF filters built into them, and so let in random RF noise from the mains. SMPS on the other hand, employ multiple RF filters and so suppress random RF noise. Batteries have almost zero RF noise (a 12v car battery is particularly good). The mains power has large levels of random RF noise from any device that has a processor, to florescent light bulbs (any plasma creates wideband random RF noise), so using a battery will completely isolate you from mains random RF noise.
So using a LPS categorically will increase noise floor modulation, giving you a brighter sound quality and degrading musicality; if you prefer that sound then so be it, but you are "preferring" distortion.
I fail to see how a LPS can supply cleaner power than a battery. As long as the battery (not battery pak) is sized properly to supply transient loads without folding. Besides the power supply for the TT2 is internal. If one wants to see if the supplied smps has an effect on sound, simply pull the plug from the back of the TT2 and listen for 20-30 sec from internal power only. Other equipment ymmv.
Absolutely - even more so if you use a 300A car battery - zero RF noise, huge levels of dynamic currents. But the tweakers will still prefer their LPS - just random RF noise sources to artificially spice up the sound.
