Madrigal Audio Proceed Manual - Using The Dap
17
Using the DAP
Input Selection
The DAP has five digital inputs. Using the
up/down buttons
, you may scroll
through the five inputs in either direction. The number of the selected input
will be shown in the center of the
main display
,
while the sampling frequency
the DAP has locked onto is displayed on the right side. (If no digital audio sig-
nal is available, the sampling frequency portion of the display will show two
hyphens (“- -”) to indicate the lack of DAS.) The digital data from the selected
input is also automatically made available to whatever device is connected to
the DAP’s
digital output
.
Volume Control
The DAP may be placed in its variable output mode of operation by pressing
the
mode button
, at which time the sampling frequency display within the
main display will be replaced by a relative volume scale which runs from 0-99.
Through most of the useful range of this scale, the increments are slightly
more than
1
⁄
2
dB per step, providing excellent volume resolution.
Many audiophiles assume that having fewer components in the signal path au-
tomatically and always means better sound quality: simpler is better. While
there is some merit to this concept, it is often taken too far. Specifically, vol-
ume control is best done in the analog domain, in a high quality active pream-
plifier. The reasons for this fact are fairly straightforward.
• “Digital” volume controls (volume control performed in the digi-
tal domain)—even extremely good ones such as the implemen-
tation in the DAP—reduce volume by scaling down the numbers
which represent the music. In this process, some low level infor-
mation is inevitably lost. While this loss can be partially miti-
gated by techniques such as those in the DAP, it is impossible to
completely avoid some loss of musical information if any signifi-
cant volume reduction is performed in the digital domain.
• Volume controls performed in the analog side of the circuit that
are passive in nature (so-called “passive preamps”) vary the ef-
fective output impedance of the processor by inserting an addi-
tional, variable resistance between the processor and the power
amplifier. This variable output impedance makes these systems
unduly cable sensitive and often changes the sound of the sys-
tem as a function of the volume setting. This inconsistency can
hardly be considered high performance.
• By contrast, a high quality active preamplifier serves as a buffer
between all sources and the power amplifier and provides con-
sistently high performance at all volume levels and with all
sources.
For the reasons outlined above, it is recommended that the variable output
mode of the DAP be used as a “stopgap” measure rather than as the primary
mode of operation. If your preamplifier fails, or if you are still saving up for a
high quality preamplifier, the DAP’s variable output level circuitry will provide
performance which is unsurpassed among digital volume controls. For the fin-
est musical performance (particularly reproduction of low-level information
such as hall ambience, etc.), use a high quality preamplifier such as the Pro-
ceed PRE or PAV, and leave the output of the DAP at maximum.