Preamp-power amp interconnectors advice

@Jafox (and others): That might be (and probably is) a flawed electronics somewhere in my system; however, I don’t think that the CA-7A, a flagship preamp from Nakamichi is intrinsically flawed. This might not be just a bad preamp design, period. This particular CA-7A might need more tune-up or replacement of some parts. Alternatively, some other component(s) of my system should be replaced (e.g., Luxman with dedicated power amp). All specific suggestions and comments on this subject are welcomed.

What is NOT WELCOMED though are comments on what priorities I should or should not have and what type of gear I should or should not use in my system, no matter how obsolete you think they are. You set priorities for your own system and other people set priorities for theirs.

@Almarg: Thanks for the suggestion to use high-capacitance cables. I have A DMM with capacitance test function and will test cables on hand. However, I would not like to sacrifice the bass output for things like soundstage or dynamics so cheap $20 high-capacitance cables might not be the best thing to use…

To all: The preamp got a dedicated power cord five days ago and it results in a DRAMATIC improvement of sound. Missing bass and lower midrange appeared; in fact, in some records I hear too much or “muggy” lower midrange. The cord is nothing special, Audio Thrills with the retail (new) around $70 or so. I didn’t believe in power cords importance for low power consumption gear such as preamps before.

Prophos: If you're not willing to take the positive suggestions and advice as well as a very different viewpoint here than yours, you're on the wrong site.
Your priorities are indeed your own. But to claim dynamics and bottom-octave bass and any kind of reasonable soundstage attributes with a cassette source is silly at best relative to LP and digital sources. Chasing cables and noting capacitance in this implementation is futile. $100 cables will be so compromised and not any less so than $20 cables.

Hope it all works out for you.

Inna: You are right. He's heard enough criticism. Now he's on his own.

If you're planning on upgrading the amp and/or preamp anytime soon I'd personally skip this step and focus on getting the components right. However, if that's not going to happen for a while and you're just looking to find a way to live happier with this setup you might stretch your budget a bit and try the Acoustic Zen Matrix Reference. The original version (i.e. not the Reference II) would probably work best since they're quite a bit more laid back in the treble and richer and fuller in the mids and bass. And they're probably a little cheaper than the Matrix Reference II if you can find them. Looks like they can be had for $250 - $300 used, and if they don't work you can probably sell them fairly easily for little or no loss. Best of luck.