Just about to pull the trigger on Pontus 15th ...

@sls883 During this time while I were torn among Harmony uDAC, Gustard X26 iii and DF 15th, I acquired Topping D90 iii Discrete to try and I like it.  It has very good separation, good layering, 3D palpability I am craving for.  The high notes notes are so intricated that I heard something that I never heard before.  The SS is not wider than the cheaper dac I had and that is not bad thing, because the notes are outlined and positioned much better yielding more defined sense of stage.  The bass notes are more weighty and nimble.  I actually turn off the PEQ and found the tonal balance from low ends are still kept.  I may keep it in the 2nd system.

I also tried smsl po100 pro ddc bet. the Ultra and D90 using I2s and got better result as expected.  I also tried CA Mxn10 feeding rca to D90 and the combo sounds the best to my ears.

The review from one of the trustworthy reviewers was finally released and gave uDAC very high remark.  He specifically compared the uDAC with D90 discrete and conclude they perform equally well in many technical aspects but are distinct in terms of sound color (warmth) and choice will be users’ preference dependent. (uDAC is warmer).  I may retain D90 since the violin / piano sounds more natural / accurate to my ears.  I do not wish the violin sound to be tamed down by a warmer DAC.

If the Gustard X26 iii is elected and auditioned in the near future for my 1st system, the stuffs we were talking about will follow through, i.e., DDC w/ clock in (uDDC / U18 / SU2) and the 10mhz master (Lhy ock2) plus Smsl pl200T (w/ a clock in).  I will need 3 clock in and Lhy is the only choice.  A lot of gears to be acquired for a slow thinker. 

@mattw73 The seemingly random, non-time-of-day pattern you've described is indeed puzzling. Given that your equipment has already exhibited qualities like a three-dimensional soundstage and full-bodied tonality, it's likely that the gear has undergone sufficient break-in. This leads me to consider whether the issue might be related to power supply fluctuations. Do you currently use a power conditioner?

@lanx0003 Glad that you found something that you like. I haven't heard the Topping D90, but I frequently read good things about it. 

@lanx0003 I think that you bringing up power supply fluctuations was a great thought. This is exactly what I have been thinking about the last couple weeks. Honestly I just didn't go into it as I didn't know what others may think. I was also wondering if this is an issue with the internal power supply of the dac? 

When the dac seems to be hitting on all cylinders like I described, the output of the dac seems to be stronger. More volume though the volume knob hasn't been touched. Like the output voltage is fluctuating from day to day. 

I do not use a conditioner on my main pieces (Dac, Pre, Amp, Sub) Those are basically running off the wall outlet thru a basic Furman box. All of my sources & anything with a Switch Mode PS runs thru one of those $500 dollar Panamax jobbies. My wall output voltage has been running high as I've been keeping an eye on it & testing it. As high as 128v but mostly between 121v-126v. I have been looking at different conditioners & voltage regulators lately. 

I'm not sure what to think. But I do strongly feel like when the Dac sounds it's best the signal is stronger or louder to the preamp. It has left me wondering if this is a Dac issue or the power that is feeding the dac. I don't have experience in this domain. 

@mattw73  I am no electric engineer (civil eng.) but looking at source for ANSI C84.1 which is the the national standard for utility voltage tolerance in North America (see below), it seems the normal range for continuous use of electrical device on user end is 110v - 126 v (+5%) and variation outside this range should be infrequent.  Sensitive electronic devices will be more vulnerable to the variations.  Not sure if this needs attention but just pass it on fyi.

https://voltage-disturbance.com/voltage-quality/voltage-tolerance-standard-ansi-c84-1/