Preamp-power amp interconnectors advice

I have a Nakamichi CA-7A preamp that feeds into the power amp section of a Luxman R-117 receiver. In this setup, highs and upper midrange are a bit bright while lower midrange and bass are not as strong as I would like them to be.

The CA-7A and Luxman are now connected with an Atlas Equator MK II cables that are considered “neutral”. If I use silver cables instead, the sound is very harsh and bass/lower midrange almost disappear. This leads me to suggestion that a cable that is a bit on the “dark” side, or the one with bass/lower midrange sonic signature, might be the best for this setup.

Any recommendations on such a cable with the price around $100-150 used?

Thank you,
I think you are expecting too much from the receiver; I would put the money toward a better power amp.
Yeah, why don't you get something like Nakamichi PA-5 or PA-7 power amp and then upgrade the cables?
Luxman will be replaced later with something like Nak PA-5 or Yamaha B-2 but it will stay in a system for a while. BTW it's not that bad of a receiver: 170 WPC, dual mono design except primary transformer winding, fully recapped etc.

The problem is IMHO that CA-7A is a bright preamp and this brightness should be be attenuated somehow ragrdless of what power amp I'll use.
If that is the case and you don't really like the sound of the pre then I would sell it and get another rather than trying to alter its sound with cables. Cables can alter the sound somewhat but not change the basic chacterstics of the unit.
Yes, Stanwal is right. That's exactly what I would do.
But if you insist, and I hate to make this recomendation for a few reasons, Cardas cables may give you that.
Thank you everyone for suggestions,

I'd like to keep this preamp at least for a while for several reasons.

One is that there is more in its sound that I like than what I dislike. The soundstage is great and instrument separation is just incredible, IMHO due to dual mono design.

Another reason is that CA-7A is a "control" preamp, allowing to remotely operate another Nakamichi gear connected to it. I found this feature very convenient to control my Nak Dragon.

Finally, what I hear now is a sound of a "stock" CA-7A version which I believe could be improved with modification of circuits or just simple things such another (dedicated) power cord or an interconnector cable. It worked well in the past and so I hope it will also work well this time.

I will try some Cardas cables, starting with Crosslink, and also Audio Metallurgy GA-0, Audioquest Diamondback and perhaps some others.

Stay tuned!
Prophos: You seek advice for a solution to deal with your flawed electronics. And yet you dismiss the idea to change these products.

I can understand the convenience of "control", but compromise the performance of a system in the year 2011 for the sake of a cassette player? Really? As long as convenience is your priority, sound quality will always take a back seat.

Many of us started at the low end with the infamous japanese receiver, budget turntable and/or CD player and equally compromising speakers. But in time we discovered the benefits of the midfi products from Adcom, PS Audio, etc., which took the system performance up a notch. We lost many "features" with this change, but the sonic benefits outweighed these. And then we step into the top tiers of performance .... it can be very impressive. But the result is due to the focus on sound, not "features" or conveniences. We all have our favorite brands or product lines, but willingness to let go and appreciate the benefits of the next tier of components is what allows us to achieve the improvements.

The flaws that you want to resolve are just not going to happen with cable swapping. Trying to mask or correct for tonality flaws in the system with cable changes is a forever-losing battle. No $100-150 cable is going to resolve your problem. You're a lot better off with $20 Monster cable products from Best Buy and put your focus elsewhere.

Tonal coherency should be your focus with the electronics, sources and speakers. Once you improve on this, I think your "soundstage" attributes will take a step up unexpectedly. Praising soundstage performance but dealing with tonal coherency flaws seems a bit goofy anyway.

The soundstage is great and instrument separation is just incredible, IMHO due to dual mono design.
"Dual mono" implementation here is more about marketing than benefit. There are many amps and preamps out there that share a common power supply for the two channels, that mightily outperform your electronics.
I agree with the responses by the others. But given that you want to try to reduce the brightness by changing cables, my suggestion is that before investing in quality audiophile-oriented cables you first try the cheapest and lowest quality non-audiophile cable you can find, the kind that looks like this.

The reason I say that is that the capacitance of that kind of cable is likely to be far higher than the capacitance of an audiophile-oriented cable, which in conjunction with the relatively high output impedance of your preamp will soften the upper treble at least slightly. (The CA-7A's output impedance is shown here as being either 600 or 800 ohms; I can't quite tell which, looking at the blurry pdf scan).

See this tabulation of the capacitance per unit length of various cable types, indicating 94 pf/ft for that generic cable, which is several times as great as the capacitance of typical audiophile-oriented cables.

The magnitude of that effect will increase in proportion to the cable length that you use. Obviously, though, longer length might increase other cable effects that would be adverse.

In any event, giving that a try certainly won't cost much!

-- Al
@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.
I think he is listening, but we just threw too much of an authority at the man, and naturally he doesn't like it. Who would?
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.