After months of (not very much) patience, I finally succeeded in hunting down the rest of the used MA700 amplifiers I wanted to complete our home theater system at a reasonable price.
This is our home theater core; a Marantz AV7005, which is a preamp / processor unit, and nine MA700 monoblock amplifiers configured for 2,000 watts RMS.
The AV7005 is a current (as of the end of 2011) model; the MA700's are a generation back, but still work with the AV7005's remote control system (D-Bus.)
I've set it all up as a 7.1 system with center, fronts, surrounds and backs at 8 ohms and 200 watts RMS each, while the sub is a pair of 18" units, with a bridged pair of MA700s dedicated to them capable of 600 watts RMS.
The AV7005 is an 9.1 / 7.1 / 5.1 / stereo preamp-processor. It offers USB, XPort, six HDMI inputs, two HDMI outputs, four component inputs, two component outputs, five composite inputs, three composite outputs, two coaxial audio inputs, two optical audio inputs, an optical audio output for recording, a 7.1 channel "aux" input, AM, FM, HD/AM and HD/FM, Internet radio, Pandora client, upnp/DLNA media client, Rhapsody client, iPod/iPad client, Sirius satellite radio client, Apple Airplay client, USB media client, balanced and unbalanced outputs, D-Bus remote control, RS-232 remote control for automation, and 12v trigger in and out for things like screen drop/retract automation, dual front panel displays (one may be hidden), and an illuminated learning remote. It pulls about 60 watts maximum, or 0.2 watts on standby, with a linear power supply that eliminates RFI problems associated with switchers. It uses a wired Ethernet connection for its network functions, may be configured for DHCP or static network connections, and can be remote controlled from a web page provided by an on-board web server, or via a telnet connection if you want to handle things programatically. Both full-page and iPod sized web control systems are provided. It can drive two video zones and three audio zones. It features Audyssey room measurement and compensation, along with by-mode and by-input channel level, tone and equalization. It also has a built-in high end headphone amp (very useful on a unit that has no main amplifiers.) DTS: [HD Master&High Res. Audio/ES/96/24/Discrete&Matrix6.1/Neo:6/Express] Dolby: [True HD/Digital Plus&EX/Pro Logic IIz, IIx, II/Virtual Speaker/Headphone] SACD decode. 192 KHz / 24-bit D/A and A/D conversion. Freq. Response 10 Hz-100 KHz +1/-3 dB. FM mono, 78 dB s/n. FM stereo, 68 dB s/n. HD radio (AM or FM) 85 dB s/n. Component video response, 5 Hz-60 MHz, +0/-3 dB. 22 lbs. Marantz provides a 3-year warranty for the unit to the original purchaser. An optional add-on, the RX101, allows the AV7005 to serve as a bluetooth client. System firmware upgrades are done via Ethernet, and take about five minutes on my 30 Mb/sec connection.
200 watts RMS into 8 ohms, 300 watts RMS into 4 ohms, or 600 watts RMS, bridged pair, into 8 ohms. Maximum .02% THD at full rated power, or less. Similar amplifier topology to the Marantz 15 amplifier designed by Sid Smith, except the MA700 adds a JFET differential pair cascoded with bipolar devices. D-Bus remote control; THX reference gain setting, THX certified. Unbalanced inputs, binding post outputs. Frequency response is -0.1 dB at 10 Hz, -0.07 dB at 20 KHz, and -0.5 dB at 85 KHz, all measured at one watt. Channel separation is unmeasurable and channel power vampirism is zero (monoblocks FTW), noise is 110 dB down. Absolute noise floor with input shorted is in the 5-75 uV range up to 200 KHz, except between 10 Hz and 40 Hz, where it is in the 420 nV-4uV range. Outputs are triple-parallel bipolar power devices. Power supply is classical linear, so no RFI issues. Protection is smart, with the amp choosing between protection options that include a lower voltage output winding on the power transformer, muting, speaker disconnection, or AC disconnection, depending on the problem type. Sensors monitor DC levels in the signal path, output voltage, and amplifier temperature. D-Bus remote start incorporates a 100 ms delay before passing the signal on, resulting in time-sequenced power up of multiple amplifiers and consequent lower peak source current draw. Standby (red), operate (green), settling (flashing green) LED indicators and hard power switch on front panel.
Configuring two MA700's as a bridged pair is easy: Using the provided switch, set one as master, the other as slave; plug the master's inverted audio output into the slave's normal audio input; jumper the (-) speaker terminals together; wire the speaker (+) to the master (+) and the speaker (-) to the slave (+), plug the preamp output into the master's audio input, and you're done.