Should I eliminate my preamp?

In this particular case, its a bit of apples and oranges.

The ARC is single-ended, but the Oppo has balanced capability as does the amp.

The simple fact is that balanced often sounds better because of improved cable immunity, and that the amp might sound better driven by a balanced source.

The ARC OTOH is getting a bit long in the tooth- and is certainly old enough to have filter caps failing as well as tubes.

In this case, I'd be all about dumping the preamp until its serviced out, but that is not to say that an active balanced preamp would not be able to help. Right now there are a few too many variables to be scientific about it.

Any preamp will add frequency response anomalies and distortion. You may prefer that sound to the unmodified signal, but it is good to be honest (as most of the posters in this thread have been) about what is actually going on.

One of the most misunderstood tasks of any good preamp line section is to control the interconnect cable. This reduces coloration, which is often heard as an overall thinness and loss of bass impact.

Passive controls often have the issue of effectively raising the impedance of the source by putting a resistance in series with that source. This can often have the effect of acting as if a smaller coupling cap is used in that source, causing a loss of bass impact.

A buffer for the volume control (at the very least) is required; that buffer also has to control the interconnect cable, so in practice many preamps reduce the colorations described in several previous posts, with a much smaller coloration introduced by the line stage- a net improvement overall.

"I can give you the maths if you want."

An offer that is hard to refuse, if not too complicated for my pay grade...

Here is some additional math:

With a 10K pot in series with the output coupling cap, a timing constant is introduced.

The formula for a timing constant is this:
1,000,000/Resistance x capacitance x 6.28 = F

Resistance is in ohms, capacitance in microfarads, F is frequency in Hertz and 6.28 is Pi x 2.

If you have a solid state source like a CD player, quite often it has a coupling cap at its output (probably an electrolytic capacitor). Depending on the designer's expectations, the cap is probably between 1uf and 10uf. But without knowing that, if we do know the amplifier's input impedance which has to be included, we have enough information to draw some conclusions.

If the amplifier input impedance is 10K (worst case scenario) we can see that the timing constant is raised an octave if the volume is all the way up. Depending on the design, this can introduce phase shift in the lower frequencies, which is perceived as reduced impact.

At volume control settings at less than full volume, a series resistance is introduced by the control. This effectively raises the output impedance of the source as far as the amplifier is concerned. To reduce the volume by 6 db, the control is at mid position, with 5K driving the output and 5K to ground. The series resistance thus introduced with such a low impedance load of 10K at the input of the amplifier can be audible as a reduction of dynamic punch at all frequencies.

Now the reason I mentioned the formula is that with different controls, the timing constants are different. Sometimes it works out well and sometimes it does not. But in all cases the interconnect cable is uncontrolled by such a high output impedance so its artifacts will be much more audible than if driven by a lower source impedance.

So audition is important- and its important to remember that while it might sound alright with a passive, it could well sound better (less colored for the reasons stated above) with an active. If you spent some money on the amps and speakers, it seems a shame to me to not get the most out of them.

This is an example of you get what you pay for. 

What Ralph mentioned about coupling caps above is not relevant these days, as nearly all solid state sources have been direct-coupled for years,

This statement is false, on account of the fact that a lot of solid state equipment does use coupling caps. Some does not- and then your chances of successful passive operation improve.

It's always been said by audio designers as a gauge of how good a preamp is since the mid 1900's, when separates (preamp & poweramp) entered into audio, that saying is:
 
"The best preamp should sound like a piece of wire"
 
ie: a like a direct source to amp connection.  

Just because one might want it to seem that way does not mean that is what it should be. Interconnect control is why so many people on this thread have had success with active line sections.

The bottom line is care and audition is imperative if you want the best out of the investment dollar in your equipment!

I do have a question regarding passives . The pot used in the SM Pro Nano patch I use I assume costs a few bucks . Would say a Alps volume pot have a different sound ? I would assume all passives should have a similar sound . Is there a way to alter the sound with a passive be it with different interconnects or like I mentioned different brands of pots?

@maplegrovemusic

The interconnect cable is going to make a bigger difference than the pot that is used. However, as the value of the pot used is increased, its quality becomes more audible. If using a 10K pot, the ALPs will work fine. You might want to run a nicer part if using a 100K part.

If your source is solid state, 10K is probably a safe value. If using tubes, check with the manufacturer, but often 50K will do the job.