SR-009S - Linear Tube Audio Z10e Integrated

The LTA Z10e Conforms to the Stax electrostatic headphone specification that Stax calls the “pro-bias” standard. This is a five-pin connector interface providing 580 volts of DC bias for the phones. This means that any electrostatic phone conforming to this standard can be used with this amplifier. This includes (but is not restricted to) Stax SR-007 MKII, SR-009 series, all of the Stax Lambda series, the HiFiMan Shangra-La and Shangra-La Jr phones and the Jade 2 phones, as well as the Mr. Speakers (now Dan Clark brand). There are a number of electrostatic headphones that are not compatible with this amp and these include the Koss ESP-950, the Monoprice electrostatic line, and the Sonore phones. 


This amp also, uniquely, for an electrostatic headphone amp, has two ¼-inch standard phone jacks to accept normal magnetic headphones such as the HiFiMan planar magnetic line, the Audeze line, the Sennheiser HD-800 and HD-650, Sony’s line of magnetic headphones, etc. There are two jacks because  one is designed for low efficiency phones and is labeled “Hi” for its output and can source phones that are seen as hard to drive with an output of approximately 2 Watts into a 50Ω load. This is ideal for phones like the HiFiMan Susvara which are notoriously difficult to drive. The other jack, marked “Lo” is designed for very high efficiency such as any with a rating of 93 dB or better such as the HiFiMan Ananda (93dB) and the Sony MDR-1AM2 (98dB). 


We now come to what is possibly the most unusual aspect of the Z10e’s unique design. As shown earlier, this LTA electrostatic headphone amp has, on it’s rear panel, a left and right pair of high quality German-made WBT 5-way binding posts. These are there to supply 12 Watts of class-AB power, per channel (at 8Ω), to a pair of speakers! The heart of this amp is the Berning ZOTL output transformer-less stereo amplifier circuit sporting four EL84 (6BQ5) beam-power pentodes which can drive any speaker with an efficiency of 90dB/Watt at 1 meter or better. This means that depending on one’s speaker selection, this US$6,950 unit can serve as the heart of a complete stereo system. The unique design of this amplifier allows for a long tube life of about three times of normal tube amplifiers and generates about 1/3 of the heat output. When changing tubes, they do not need to be matched.


All front-panel functions of the Z10e are accessible using the enclosed Apple hand-held remote control. This includes standby/operate, input selection, volume, and selecting between headphones or speakers. In addition, the remote can be used to set a fixed output for any selected input (for home theater operation) or to choose any of 16 different brightness levels for the display as well as programming the display timeout for 10 seconds (normally, it’s on all the time). I was able to check this aspect of the Z10e’s performance because even though my review sample did not come with a user’s manual, I was able to find one on LTA’s web site. Hopefully, the retail version does come with a full set of printed instructions (my sample was S/N 009). I must say however, that putting aside, for the moment, the lack of a printed manual, that the Z10e is quite intuitive in its set-up and operation and can be easily configured by any seasoned audiophile.

George Grave
28 January 2020