Need a preamp?

@jaferd  I'd argue that point- your system easily revealed one of the most common complaints leveled at passive controls. But the switch box doesn't seem to cause any harm?? That sounds to me like your system is revealing, and that in your case it is an elegant solution, even though it might not **look** elegant.

Ralph, any downside to source switching with CMOS electronic switches instead of relays?

Yes- there is a reason we still use mechanical switches. CMOS is pretty good- but have a higher resistance and more diode effect than actual switches.

I didn't listen to it very critically when I realized right away that it didn't sound completely transparent. I want to say maybe a tad less dynamic but YMMV. My feeling is that a preamp or anything that is introduced to a signal can only degrade it so I wasn't completely surprised. I even think a switch box wont be as good as without anything but the degradation may not be noticeable to me. I think a preamp that "improves" the sound just means that it added some colouration and/or minimized some faults to the source signal so that it sounded nicer to the reviewer. I'm sure my taste for tube sound is nothing like what the source really sounds like without any colouration. My 2 cents.

Its a lot more complicated than that! And I'm only going to put this in a nutshell:
The reason we are able to have a hifi industry is due to the ear's masking principle. The ear is keenly sensitive to higher ordered harmonics which are made by *all* electronics. Tubes tend to make more harmonic distortion in this regard, but because they also have either a 2nd or 3rd harmonic (which is substantially less with solid state), that particular distortion is able to mask the higher ordered harmonics. This is why tubes sound smoother than solid state. Solid state makes these lower harmonics also, but not as much, so they are unable to mask the higher orders *as much*.


The odd thing is that the injection of a 2nd or 3rd harmonic also allows the ear to hear better lower level detail and increased soundstage width and depth! This is why tubes generally are more detailed and have better soundstage. However, the ear also interprets distortion as tonality; if the tube electronics have *too much* of these lower orders, it can sound more 'romantic' or 'rich' than is reality. So a designer has a fine line to walk- too much distortion and the gear is 'colored'; not enough and the gear is bright and harsh.


The bottom line is we can't make amps and preamps that don't make distortion. So this masking principle is important- without it hifi would not exist. 


Passive systems OTOH have their own issues- they effectively raise the output impedance of any source (as far as the power amp is concerned) and this seems to be why impact is impaired. They can also cause high frequency rolloff; even though that rolloff and be ultrasonic, the phase shift that can be introduced is interpreted by the ear as a rolloff. To prevent this, the interaction of the control and the associated capacitances (interconnect cables) has to result in a rolloff above 200KHz.


For these reasons, a tube preamp, if designed correctly, can often sound considerably more neutral with greater low level resolution than a passive or active solid state system.

So I got the Schiit sys but it seemed to have muted the top end. Didn't sound as lively even with the volume turned all the way up.

This is also a common complaint of passive controls. I'll be interested to hear what you think of the switchbox.

Then they are kidding themselves

Actually they aren't. Loss of impact is the most common complaint aimed at passive controls (the exception being when the control is already in the power amplifier). Loss of impact is a coloration.


The problem is that in many circumstances the digital is making so much output that the volume control can't be run up to full volume, so the user is not able to find out how much impact is affected. And this doesn't happen universally. So like so many other things in audio- you just have to try it and see. But in this case, there's no point in an outboard passive control, since the OP has controls built into his amp. He only needs a switch box.

Interesting since any active preamp would seem to add some colouration.

That's a matter of intense debate. Many think that no preamp has its own colorations too (of which I mentioned earlier).

@jaferd  For slightly more money you get better connectors and hand wiring:

https://www.ebay.com/itm/4-Input-2-Output-Audio-Video-AV-RCA-Selector-Splitter-Switcher-Box-Adapter-...

Also, would either give worse sound than just switching the inputs manually and using the attenuator? Just for my own education, do passive preamp color the sound at all and what about cables? Are there any affordable, I mean in the 300 dollar range, used cables I should look for that do not add coloration?  

@jaferd  Passive controls easily color the sound if external to the amp. The most common complaint is loss of impact at anything less than full volume.  They are also more sensitive to cables. For these reasons and because you also have a control already in the amplifier, I suggested a simple switching box, which will sound better than any outboard passive you can get in your situation.

The Cary is not the most neutral preamp around IMO. So a passive would work quite well in your situation as you already know. I think you can get switch boxes to switch between inputs. Since you already have an internal volume control in the amps (which is the best way to go if you go passive) then the switch box is all you need- if switching the inputs manually is too much of a hassle.