Amp/Preamp Asylum: REVIEW: Inner Sound ESL-300 Mk. II Amplifier (SS) by rkeman

Model:	ESL-300 Mk. II
Category:	Amplifier (SS)
Suggested Retail Price:	$2995
Description:	Stereo Power Amplifier
Manufacturer URL:	Inner Sound
Manufacturer URL:	Inner Sound

Review by rkeman ( A ) on March 22, 2005 at 11:11:24
IP Address: 12.168.121.2

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for the ESL-300 Mk. II

The Innersound ESL-300 is a stereo power amplifier built by Coda Technologies in California and marketed by Innersound. It appears to be nearly identical to the Coda Stage 3.3. Rated to produce prodigious power (300/600/> 1000 w/channel into 8/4//2 ohms) and remain stable with reactive loads, the ESL-300 is an excellent candidate for driving electrostatic, planar, or conventional loudspeakers. The design is based on a 2k VA toroidal transformer and 36 (!) bipolar transistors in the output stages. The gain is specified at 26 dB, input impedance is 50k ohms, and the signal-to-noise ratio is rated at > 110 dB referenced to rated power output. The amplifier is housed in a sturdy aluminum chassis measuring 17" x 5.5" x 16" and weighs 45lbs. Both RCA and balanced XLR and RCA inputs are provided, although the inverting signal of the balanced input is simply grounded through a 50k ohm resistor. The speaker connections are via high quality WBT binding posts that will accept spades or banana plugs. The literature available from Innersound and Coda suggests that minimal feedback is used and the output section bias is minimized to insure cool operation.
In actual use, the Innersound ESL-300 delivers abundant clean power with a variety of speakers. It is equally at home with large planar speakers (Eminent Technology LFT-VIIIa and Magnepan MG-1.6) and traditional dynamic speakers (SEAS Thor). The music emerges from a black background without a hint of harshness or coloration. Bass is well controlled and extended. Image depth is true to the source with no editorial effect and dynamics are quite life-like. There is no hum from the transformer or turn on/off pops or thumps. The amplifier produces little heat, even when on for extended periods or when pushed hard.
It is hard to call any amplifier costing thousands of dollars a bargain, but if there can be such a thing, the Innersound ESL-300 would certainly qualify. It has essentially no significant sonic signature and can handle just about any load it is likely to encounter. Highly recommended.

Product Weakness: None so far.
Product Strengths: Powerful, quiet, and clean sound. Cool running and compact.

Associated Equipment for this Review:
Amplifier:	Innersound ESL-300, Ayre V-3
Preamplifier (or None if Integrated):	None
Sources (CDP/Turntable):	Benchmark DAC-1, Panasonic RP-91 DVD player, Theta Data Cd transport, Motorola HD cable box
Speakers:	ET LFT-VIIIa, SEAS Thor
Cables/Interconnects:	DIY Canare and Belden
Music Used (Genre/Selections):	Pop and classical
Room Size (LxWxH):	24 x 14 x 8
Room Comments/Treatments:	Normal furnishings
Time Period/Length of Audition:	4 months
Other (Power Conditioner etc.):	None
Type of Audition/Review:	Product Owner

Product Weakness:	None so far.
Product Strengths:	Powerful, quiet, and clean sound. Cool running and compact.