[gkinberg]

I use one system for two channel and home theater. Currently I use my Onkyo receiver as my preamp. I am considering getting a separate full function preamp with home theater bypass. However, I  was reading that if one simply plays CD’s then a preamp my not be necessary because the player already has a lot of gain. I currently only play CD’s through a sony playstation3 but also want to get into computer audio. My question is, does a preamp make sense in my situation or would I just need a volume control for example on a DAC? I would just assume not get a pre if I don’t need it but I’m not sure how else I would get my home theater bypass without it. Thanks for any insights, Garth

[srb]

One possibility would be the Wyred4Sound DAC-2 which has HT Bypass inputs to integrate with your home theatre.  The volume control, while digital, is a 32 bit volume control.  I'm not sure if there are any other DACs available that have HT Bypass inputs.
 
Steve

[JLM]

Garth,

As Steve mentions, the general rule of thumb is to avoid digital volume controls as they normally just shave off the top output peaks rather than lower all signals (low and high volume proportionally like a volume control should).  Some, again as Steve mentions, are more sophisicated.  The light based volume controls are supposed to sound really good, but have a life expectancy.

Many volume controls in integrated amps and most in DACs are passive (which means there is no associated gain/boost circuit that can lack dynamics).  Note that the upgraded Eastern Electric DAC did away with it's passive volume control.  So to answer your question, most recommend an active pre-amp.

[Ericus Rex]

+1 on avoiding digital volume controls.

And there are lots of good preamps out there for cheap these days.

[Big Red Machine]

+1 on avoiding digital volume controls.

And there are lots of good preamps out there for cheap these days.

They may not be suitable for use in this scenario, but Wavelength and other dac manufacturers (forgot the names of 2 others) have techniques for not shaving bits in the volume control.  Just to set the record straight on that item. 

[gkinberg]

Thanks for the input guys. I thought I remembered that volume adjustment was better suited in one place rather than another but wasn’t sure.

What are your thoughts though on not needing a pre if only using digital because the gain is already plenty high as compared to vinyl?

[avahifi]

In considering a DAC with a volume control of some sort connected directly to your power amp, see if you can learn a bit about the actual audio output circuits in the DAC.

A well designed active preamplifier will have relatively low output impedance and high drive current to properly drive the distributive capacitance of the interconnect cables and the input capacitance of the power amplifier, whatever these values may be.  Many DAC's analog output stages are not designed for these loads, just to look at a relatively short set of interconnects into a standard 47K ohm input load of a preamp.

Unless the DAC designer has put a lot of thought about all the interface options the DAC may see, use of a DAC without an active preamp might well lessen the fidelity of the system instead of improving it.

Frank Van Alstine

[gkinberg]

Thanks a lot Frank. Your input, as always, is appreciated.

Garth