In Barn for Review: A ModWright Stack—LS 99 Balanced Tube Preamp | KWA 99 Monoblocks

A tower of power.

The ModWright LS 99 Balanced Tube Preamplifier comes with a pair of new JJ E88CC/6DJ8 family of miniature nine-pin medium-gain dual-triodes and a single Sovtek5AR4 for the tube rectified solid state outboard power supply.

The front face is matter of fact, with two hefty dials for input selection and volume control and 4 toggle switches for Power, Mute, Phase, and to engage Home Theater Bypass mode. The included remote mimics these functions.

A total of 4 inputs (2x XLR, 2x RCA) and 4 outputs (2x XLR, 2x RCA) fill the LS 99’s backside along with a Home Theater Bypass input for movie buffs, 12V trigger outputs for leashing additional ModWrights together, and an 8-pin inlet for the outboard power supply (a 4′ umbilical cable is included).

The KWA 99 Monoblocks offer 100 Watts of MOSFET-based power into 8 Ohms, doubling down into 4, run in Class A/B but “biased as much into Class A as possible for best sound.” Just like the LS 99, the KWA 99s measure 10.5″ wide and their meter-endowed front face are joined by a single power button per side. I’m a fan of the ‘ModWright blue’ heat sinks that run along part of the outer long side and top of each ‘block.

Each KWA 99 offer a single balanced XLR and single-ended RCA input, a pair of 5-way speaker binding posts, and a 12V trigger input to control on/off status along with other function for other ModWright products, very much like the LS 99, with a single remote. A dial allows you to dim those VU meters and a toggle switch turns the internal LEDs on or off.

All in, the ModWright stack comes in at $15,500 and I’m looking forward to lighting them up and giving the stack a good, long taste with a number of speaker pairings. Stay tuned!


ModWright LS 99 Balanced Tube Preamplifier
Price: $6500
ModWright KWA 99 Monoblocks
Price: $9000/pair
Company Website: ModWright

LS 99 Features

(2) XLR Fully Balanced Inputs.
(3) RCA Inputs.
(1) RCA HT/BP (Home Theater Bypass Input).
(2) XLR Fully Balanced Outputs.
(2) RCA Outputs.
Dual Remote 12V Trigger Outputs.
Remote Control: Volume, mute and trigger outputs.
Tube Output: 6922/6DJ8/7308/E88CC
Tube Rectified: 5AR4/GZ34 and Equivalents.
Pure Class A.
External Power Supply.

LS 99 Specifications

Gain: 11dB.
Frequency Response: 20Hz – 150Khz flat.
Input Impedance: 30K.
Output Impedance: 100 ohm.
Noise Floor: -110dB (unweighted).
Dimensions: Preamp = 10.5”W x 4.5”H x 12”D. (Depth includes 1.25” knobs and .75” RCA’s. Height does not include exposed tubes. Overall height varies by tube mfr).
Dimensions: External Supply = 7”W x 9”D x 3”H
Weight: Preamp = 17 lbs. External Supply = 11 lbs.
Combined Shipping Weight: 33 lbs.
Umbilical: (1) 4 ft. umbilical with 8-pin Switchcraft connectors.

KWA 99 Features

(1) RCA input.
(1) XLR input.
RCA and XLR inputs are transformer coupled to input stage with floated ground.
(1) Pair 5-way Binding Posts – Positive (+) Red, and Negative (-) Black. Not bridged.
(1) Internal Led On/Off Switch: Disables internal LED’s.
(1) VU Dimmer Knob: Adjusts brightness of VU meter, to zero brightness.
(1) 12V Trigger: External 12V input power on/off trigger.
Class A/B Operation. High Class A bias, but not pure Class A.
Dimensions: 10.5”W x 6.5”H x 16”D – Height includes footers. Depth includes 1” binding posts.
Product Weight: 30 lbs / Shipped Weight: 35 lbs

KWA 99 Specifications

Gain: 26dB.
Frequency Response: 10Hz – 150Khz (+0, -1dB).
Input Impedance: 47K.
Noise Floor: -90dB (Unweighted).
THD: < .05%