AlphaLab LNA 10 preamplifier was mentioned in a few posts, for example here
https://www.eevblog.com/forum/projects/some-information-on-the-lna-10-low-noise-oscilloscope-amplifier/msg2682060/#msg2682060 and here
https://www.eevblog.com/forum/testgear/preamplifier-for-noise-measurements/msg3073534/#msg3073534.
It's primary advantage is low cost ($270) and rough similarity to Stanford Research SR560. So I got one for general lab use.
As shown in the picture below it uses a quad OPA4209 op-amp for the input stage. The performance is decent, but since it uses a quad op-amp, there is limited possibility to upgrade to a different chip. The power supply to the op-amps is +/- 4.5 V (derived from 12 V wall wart), so the output voltage is limited to about +/- 3V. The maximum 3dB bandwidth is about 800 kHz and can be adjusted down to 1 Hz. I was particularly interested in the noise spectrum for gains lower than maximum. Indeed, for gain of 100 the noise level remains the same as for gain of 1000, about 4 nV/Hz^(1/2). For gain of 10 the noise level increases to about 10 nV/Hz^(1/2). This is about the same as for SR560.
The current noise of the amplifier is however larger than for SR560. Shorting the input with a 1 MOhm resistor (instead of a dead short) gives the noise of about 200 nV/Hz^(1/2) vs. Johnson noise of 127 nV/Hz^(1/2). In contrast, according to specs SR560 has a noise figure close to 0 dB for 1 MOhm source impedance. The current noise of LNA10 can be estimated to be about 0.2 pA/Hz^(1/2), which actually seems somewhat smaller than the spec of OPA4209 op-amp of 0.5 pA/Hz^(1/2).
The noise level and the amount of 60 Hz pick-up did not change appreciably when I switched from wall power to a 12V battery to power the amplifier. The amplifier output data were acquired with MAX11410 evaluation board (a free giveaway from Maxim a few years ago).
The build quality seems pretty good, BNC connectors are of decent quality and the knobs seem solid. However, my unit seemed to occasionally produce glitches, which consistently went away when I turned the box face down. This was the case both before and after I opened the amplifier.
So overall the performance of LNA10 is pretty good, matching most features of SR560, except the input current noise, at a 10th of the cost. It is perhaps not state-of-the art, but a very good deal for a general purpose pre-amplifier.