06-26-10: Krellfan2002
I have a Wadia S7i at home and play with the Pass XP20 and XA160.5 but I prefer the preamp. Without the preamp I miss some body and dynamics. For me the preamp adds something.
the statement above makes absolutely no sense to me. the preamp can only work with the signal being provided by the source signal. so if the preamp "adds something" then what it is doing is coloring the source signal.
wadia provides variable outputs where the preamplification is performed in the digital domain. the biggest problem that i have observed is when you adjust the variable output level too low. in theory, once you get below an output level of 65, you are starting to lose significant bits in the digital stream. in theory this would translate into less resolution. if you are at an output level of 75 or above, you probably aren't losing any significant bits.
the other problem that you can encounter with direct connection is that with some low volume level source material (typically classical recordings since volume level is rarely a problem with popular recordings) the playback volume can be lower in comparison to connection through a preamp. by default wadia provides an output voltage of about 2vrms (i assume this is the output measured from the single-ended outputs and so i assume that the default is about 4vrms when using balanced outputs). as i stated, this is adequate for most recordings (for reference, power amplifier gain is usually measured based on a single-ended input signal level of about 2vrms). however, if it isn't the volume can be adjusted to produce a voltage output of up to 4.25vrms by setting all the internal DIP switches to the "open" position. if that output level is still not sufficient for the source material, then you would need to use a preamplifier. but presumably, in this case you are using the preamplifier to provide additional signal amplification with accurate reproduction of the source, as opposed to provide coloring of the source.
of course, if coloring is what you want in your preamplifier (which is basically what you get with tube amplification) then that is entirely legitimate since all this stuff is a matter of personal preference. the point i am trying to make is that if you seek "transparency", then you aren't going to do better than direct connection from the wadia to the power amplifier; the potential limitation being that the direct connection may provide insufficient signal gain depending on the source material.
