If You Were A Swine Looking To Choose Between 3 Preamps...

P.S: I subsequently found the following output impedance spec for the Line Magnetic preamp:

Output impedance: 600kΩ balance output 600Ω (RCA)

The 600kΩ spec is nonsense, as the design wouldn’t work with that kind of output impedance. The 600Ω number is probably based on a mid-range frequency such as 1 kHz, but given that the preamp’s output is transformer coupled its output impedance probably doesn’t vary greatly at other frequencies (as it probably would if the output were capacitively coupled). So it **might** be marginally suitable for use with an 8K load.

Regards,
-- Al

Swine - you don't mention price or budget.  A used Allnic will probably cost more than a new Herron Audio VTSP-360 and will likely NOT outperform the Herron.

almarg -  I appreciate your analytic advice.  I'm using Parasound JC 1 monoblocks (100 kΩ bal input) with a JC 2 BP preamp (60 Ω output). I'm trying to predict how well the JC 1s might pair with a Ayre KX-5 Twenty preamp, but Ayre doesn't include output impedance in the specs.  I'm currently using the Ayre preamp with a VX-5 Twenty (2MΩ bal input) stereo amp, but expect to consolidate two setups into one in the future.

db 

@dbphd    Nearly all preamps will be able to handle a balanced input impedance of 100K with no problem. And that is certainly true in the case of the Ayre KX-5 Twenty, which per Stereophile's measurements has a balanced output impedance of about 156 ohms at all audible frequencies.

However, I see in those measurements that the Ayre provides essentially zero gain for its balanced output (and negative gain from its unbalanced input to its unbalanced output). While your JC2 BP provides 14 db of gain (with its volume control at max). So with the Ayre you will find yourself having to turn the volume control up to a significantly higher position than you are used to.

If the minimum setting of the volume control on the JC2 BP is around the 6:30 or 7 o'clock position, and the maximum setting is around the 5 or 5:30 o'clock position, a 14 db change probably corresponds to a little more than 90 degrees of rotation. If you presently use volume control settings in the top third or so of the range of the volume control on the JC2 BP, the Ayre's lack of gain would be a definite concern.

Best regards,
-- Al