DACs and bass response?

As I understand it the J-test was developed by Julian Dunn in the mid 90’s.

It appears to be the best test found so far and is used by AP in their lab test gear. (I dont agree with probes on legs of DAC chips as the probe itself is likely to affect the device itself when measuring timing to such accuracy. I think the J-test known test signal in and a careful look at the perfection of the analog out is much more representative as it tests the DAC as a whole as it is designed to function and including the clock timing accuracy)

A LSB square wave at Fs/192 which produces harmonics right across the audio range. This square wave is coupled with a high level sine wave at Fs/4. The sine wave being a very intense digital full on/off work out (nasty stuff that should produce logic Induced modulation in anything but stellar equipment)

Looks like an extreme DAC jitter work out or jitter stress test to me!

No doubt jitter is still there even on the best devices but to have analog artifacts of jitter sitting below a -150dBfs noise floor seems exceptionally good to me.

https://www.stereophile.com/content/case-jitters

@georgehifi: forgive my ignorance, but would installing such a cap likely void warrantee? Also, is this something I could purchase from say, parts conneXion?  Briefly, what is involved in installation? Thanks. 

BTW, I swapped out power cord and coax cable for another brand and it substantially helped the La Voce's bass. Disappointingly, swapping out cables did nothing to improve the muddiness of the Adagio in my system. There must be a profound lack of synergy. It's going back. 

@audioengr

I believe your Synchro-Mesh works as you claim from your measurements. I have no hesitation recommending it as I know others with excellent DACs that benefit from source jitter reduction devices including cables.

I also believe many (most) DACs are not at all good at jitter rejection and also have high intrinsic jitter (despite claims to the contrary). So the Synchro-Mesh is a great product for improving sound quality of most DACs.

Since you are clearly able to build a device that takes 800 psec jitter from an Oppo and turn that into 20 psec jitter with your Synchro-Mesh, then why do you believe that nobody else has a DAC that can correct incoming jitter to completely inaudible levels - around 20 psec or less?

stuartk OP158 posts
georgehifi: forgive my ignorance, but would installing such a cap likely void warrantee? Also, is this something I could purchase from say, parts conneXion? Briefly, what is involved in installation? Thanks.

Hi Stuart, if you need to ask this. Better off getting some one to do it, it’s not hard.

Cheers George

PS Stuart just found a good internal pic, click on the pic and it enlarges again, and the two blue plastic caps are the ones near the output rca's, but unfortunate they are already 3.3uf and are quite big enough, but of cheap industrial quality, this is why some owners are changing them for more upmarket caps, maybe this also could help the bass??
http://www.6moons.com/audioreviews/aqua/9_big.jpg

Cheers George

@georgehifi : yeah; I am not at all mechanically minded, so what you you offer is, indeed, "sound advice"!  Thanks for the pic.