Equipment and Music mentioned on our review page

Here is the link to our review page:
http://www.digitalamp.com/DAC_REVIEWS.htm

Here are a few lists of mentioned items in categories...

Speakers:
Dennis Murphy
Canton Karrat
Apogee Caliper Signatures
ACI Sapphire
Magnepan MG1.6
Gradient Helsinki 1.5
B&W 805s
SPTech Minis
Von Schweikert VR-4SR MKii
Von Schweikert VR4JR
VAC PA100/100 amp
Joseph Audio RM7si
Quad ESL 57
Quad 22L2
Ohm5 MKii
Advent lG
Bose sub/sat (unknown model)
Hafler 300 Series

Amps:
Pioneer/Luxman Hybrid Amps
Denon
Parasound
NAD
Manley Stingray Integrated Tube Amp
Conrad Johnson CAV 50 Integrated Tube Amp
Cary Slam 100 Mono Blocks
AVA Insight 440H
ICE-based H2O Audio S250 Signature
Exodus Audio UcD400
Aberdeen Signature TacT S2150
PrimaLuna tube integrated
Channel Island D200s
Sunfire Signature 600 watt
Aragon 2004
Pass Labs
Nuforce
Nakamichi PA-7 (stasis)
DAC 4800a
DAC4800A
Cherry
DAC/Cherry

Preamps and D/A:
MacIntosh tube pre-amp
Bel Canto pre-3
NAD C160 preamp
Jeff Rowland Capri
Bel Canto PRe3
Red Wine Isabella DAC/PRE
VAC Standard MKII preamp
Promitheus TVC rev 3 passive preamp
DACT CT-1 (volume control pot)

Cables:
Theils and Silver Cabling
Balanced KCI Gold Cable
Black Sand Silver Ref V Power Cord
VandenHul carbon fiber interconnects
DIY 8’ Axon cables

Misc Equipment:
Shanling T200A SACD Player
Audio Technica AT440MLa Cartridge
Adcom GFT-555 II Tuner
Rotel 1072 CD Player
Resolution Audio CD55 Player
Misc Terms:
Pro-Ject Perspective Carbon
Tube Box SE
GIK, 8th Nerve panels
Reality ICs
Black Sand PCs
PRAT, pace rhythm and timing
CLDjam
1.5" thick, braced walls on heavy 24"steel stands
350w into 8ohms and almost 700w at 4ohms
15A breaker
XLR inputs
binding posts
removable IEC plug
750VA torroidal transformer
1500VA transformer
thermal, shorted, voltage and over current protection
standby/operate switch

Music:
Dire Straights "Love over Gold"
Cowboy Junkies "Trinity Sessions", "Mining for Gold" (Margo Timmins solo), "Misguided Angel"
Portishead "Dummy", "Mysterons"
Peter Murphy "Deep", "Marlene Dietrich's Favorite Poem"
Yello
Everything but the Girl
Peter Gabiel "Shaking the Tree"
Monster Magnet "God Says No"
Radiohead "Kid A"
Delerium "Poem", "Aria"
Paganini Caprices
Bach's great organ works
Rob Wasserman’s Duets "Angel Eyes"
Ani Difranco’s "Garden of Simple" and "So What"
Ben Harpers "Fight for your mind" title song, as well as "Burn one down" portrays the drums with excellent speed and timbre. Impressive!
The Trinity Session by Cowboy Junkies
Patricia Barbers Modern Cool, "Company"
Red Rose Music vol 1 track 6 (twenty-third psalm, Shane Cattrall)
The Belfast Harp Orchestra, Earth Water Wind and Fire
McIntosh Test Disc "Voices of Angels" (Track 5)
David Manley recordings #8 Cantos de los Gitanos
Diana Krall
Tsuyoshi Yamamoto (piano)
Boston Pops
Cincinnati Orchestra
Pink Floyd
Eva Cassidy "You take my breath away"
Rebecca Pigeon "Spanish Harlem"
"The worlds Greatest Audiophile Vocal Recordings" produced by Chesky records
Red Rose Recordings "In a sentimental mood", "Misty"
George Winston "Autumn"
The Grande Piano Concert by Rick Wakeman
Red Rose "Recitative in Scherzo for Solo Violin" (track 4)
Ottmar Liebert + Luna Negra's "Viva", "Buddhas Flower" (track 2)Stravinsky's "Firebird Suite"
Tchaikovsky's "1812 overture", "Fanfare for the Common Man"
Dagda "Druids in the Glen"
Pink Floyd "Dark Side of the Moon"

Slew Rate of DAC4800A and Cherry

The DAC4800A and Cherry amplifiers are "switching amps", so technically, the internal slew rate is that of the output stage (about 7200V/uS). The output filter of the amp removes the switching wave and yields an output slew rate of about 20V/uS (with an 8 ohm load). This is a respectable number, but keep in mind that it is limited by the output filter and increases as load impedance goes down.

The frequency response goes up to 60KHz on the DAC4800A and Cherry amps. This is a more valuable number than slew rate to many.

The sound of these amps can't be summed up with measurements (even though they are excellent) since they are designed from the ground up to deliver the best in music reproduction, not just test results in a lab.

Line Conditioners?

The DAC4800A and Cherry are designed to tolerate large AC mains fluctuations so you shouldn't need any line conditioning (save some money there). In fact, these amps even tolerate brief brown outs, playing through them without any noticeable effect.

About Speaker Cables --- They Don't Need to Cost a Fortune!

It comes down to resistance and inductance. If you can solder, buy 12 gauge or 14 gauge (if the run length is less than 15 feet) wire and get terminations from Digi-Key. By terminations, I mean banana plugs or spade lugs. I definitely recommend soldered connections instead of crimped for long life. I agree that this is a typical area for spending too much when it really doesn't make a difference to the sound or your system. This comes from an engineer with 20 years experience, not a marketing firm.

Audio Review Still Hasn't Responded

We tried to add the DAC4800A amplifier (see http://www.digitalamp.com/4800a_amp1.htm) to Audio Review so we can get customers to add reviews there. However, there is no selection for adding a new manufacturer. The listing shows up with "unknown" as the manufacturer. Here's the link:
http://www.audioreview.com/cat/amplification/amplifiers/unknown/dac4800a/PRD_419903_1583crx.aspx

We wrote to them, but no reply. We posted to the help board, but the post was removed.

Does anyone know somebody in charge at Audio Review? We would like to get on the manufacturers list. Locking us out is just not fair. Thanks.

Why Our Amps Sound Better

Some of our customers have told us that they love the sound of our digital (technically "Class-D") amps, but they don't like the sound of other digital amps (from other companies). It might be the output filter or feedback design. People often criticize me for saying that feedback wrapped around the output filter of a Class-D amp can have a negative impact on the sound. Actually, this could be your answer!

By the way, fake class designations like "Class-T" or "Class-Z" are actually Class-D. The definition of "Class-D amplifier" is "an amplifier that uses its output devices as switches". This is a pet peeve of mine.

Thanks for hearing me out.

Switching Amplifier Output Ripple Doesn't "Fold Down"

Regarding "folding down", this is called aliasing and is explained by sampling theory. Here is a basic explanation:
http://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem#Aliasing

Aliasing only happens when the waveform is sampled, which is not the case for a switching amplifier output driving a loudspeaker. The time domain output waveform of a switching amplifier (after the output filter) has switching ripple superimposed on top of the audio. The ripple is ultrasonic, so it is not heard. The mechanical limitations of loudspeakers do not allow this superimposed waveform to enter the room, not that it would matter anyway, as long as the switching frequency (Fsw) is high enough (>100KHz). Most switching amps change states (switch) at a rate of 350KHz or greater. Higher switching rates cause additional EMI and lower efficiency, and lower rates are harder to filter. The power dissipated in the loudspeaker by the ripple is typically a few milliwatts.

In order to accurately measure the performance of a switching amplifier, a filter that removes most of the ripple is usually placed between the amplifier under test and the measurement device. Such a filter requires flat response out to 20KHz or greater, but a rapid fall-off by the 100KHz range. Attempting to measure a switching amplifier without such a filter can drive the measurement equipment nuts as it tries to sync to the amplifier's output ripple instead of the audio signal.