Should I eliminate my preamp?


I have been using my Audio Research tube preamp and Bryston amp to drive Magnepan speakers for years. Recently I added a Oppo blue ray player to my system and connected directly to my amp using the balance cables. The reason was to eliminate the signal having to go through another piece of equipment before it hits the amp. Am I wrong or what am I missing?
elf1
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.
The OP was asking about getting rid of the preamp in the case when the DAC has a volume control. In that case, there is no downstream volume control, and no need to provide a low impedance buffer for the interconnect, as the amplifier will take care of that.
The OP was asking about getting rid of the preamp in the case when the DAC has a volume control. In that case, there is no downstream volume control, and no need to provide a low impedance buffer for the interconnect, as the amplifier will take care of that.
This is correct, and the source having a digital domain VC it will have a low impedance output, probably lower than many preamps especially tube ones, and it will drive any interconnect just as well if not better.
Besides, driving interconnects with a 10kohm passive is not an issue either, unless the interconnects are"low quality high capacitance" and are 3mt or more long. I can give you the maths if you want. 

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

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

I like 10kohm pots as passives, as the can be driven by just about any solid state source, just some high impedance tube sources have trouble, and being 10kohm as a voltage divider passive they have the lowest output impedance at worst (mid possition) around 2.5kohm.

With 2mt of poor quality interconnect with high capacitance at (100pf picofarad per ft) that 2mt is approx 650pf total

6.28 (2 pie) x 2500ohms (2.5k) x 650 (650pF) ee to the -12 1/x = gives a very respectable -3db point at 98khz! and this is the worst interconnect at 2mt at the worst mid volume setting.

So as you can see driving the capacitance of poor quality 2mt interconnects with a 10kohm passive at worst volume mid position of 2.5kohm Z is not an issue at all as we are at only -3db at a still very high 98khz!

With one meter of that same interconnect, it becomes -3db at 196khz!!

With one meter of better quality interconnect which has only 50pf per foot then the -3db is at 392khz!!!!   

Cheers George