Sonic impressions of TG Audio 688 power cord?

Anybody auditioned TG Audio's new 688 power cord?

Anybody directly compared it to TG Audio's SLVR power cord?
The 688 sounds like the SLVR , but lacks a small amount of the SLVR's bass response. At least that's what I hear so far. I have a SLVR on my digital source and a 688 on my preamp where the SLVR was briefly. I have another 688 cooking/breakin on my work puter monitor. My 688s were a HSRa and a HSRi that Bob upgraded to 688s.Even he says that the 688 is too good (close to SLVR ).
Do you know if the only difference between the 688 and SLVR is the silver-plated contacts? Or are there more significant mechanical differences?
Claud, sounds like the 688s aren't broken in all the way as biggest difference is the focus of the SLVR over the 688 here....There are enough mechanical differences between the 688 and SLVR that I can't easily update the 688s to SLVRs and don't offer this....I probably should not have offered to do take the HSR-I to 688, but can do these as required.....Mshan, the metalwork in the P&S dielectric is now custom made for both the 688 and the SLVR....

Bob Crump
TG Audio/CTC Builders/DDR Mfg