Oscilloscope to calibrate compressor?

Hello....I appreciate that there have been numerous oscilloscope threads but I would really appreciate some help here.  I put together one of Jeff's FC526 Compressors some time ago but have never calibrated it.

I would like to put together several more as well as Volker's LA2A

An oscilloscope would be used for this purpose only, at least as far as my current needs dictate.  There seems to be many options including both the traditional bench top and newer USB styles.

Have been looking at the following and would appreciate some guidance.

There are  not any electronics rental shops around here so that is not an option

Diligent Analog Discovery 2  $280
http://store.digilentinc.com/analog-discovery-2-100msps-usb-oscilloscope-logic-analyzer-and-variable-power-supply/

VDS1022I 25MHz 2+1 Channel PC USB Oscilloscope, MIT USB Isolation  $107
https://www.sainsmart.com/products/owon-vds1022i-25mhz-2-1-channel-pc-usb-oscilloscope-mit-usb-isolation

Hantek  $109
https://www.amazon.com/Based-USBXI-Digital-Oscilloscope-Analyzer/dp/B01M30MIPK/ref=sr_1_2_sspa?ie=UTF8&qid=1508683502&sr=8-2-spons&keywords=usb+oscilloscope&psc=1

Hantek DSO5102P  $230
https://www.amazon.com/Hantek-DSO5102P-Digital-Oscilloscope-Channels/dp/B00QROKLWA/ref=sr_1_8?s=industrial&ie=UTF8&qid=1508686563&sr=1-8&keywords=hantek+oscilloscope

Rigol DS1102E  $364
https://www.amazon.com/Rigol-DS1102E-Digital-Oscilloscopes-Bandwidth/dp/B001VKCJ0M/ref=sr_1_3?s=industrial&ie=UTF8&qid=1508683722&sr=1-3&keywords=rigol

Rigol DS1054Z  $400
https://www.amazon.com/Rigol-DS1054Z-Digital-Oscilloscope-Channels/dp/B012938E76/ref=sr_1_1?s=industrial&ie=UTF8&qid=1508683722&sr=1-1&keywords=rigol

I appreciate that these cover a broad range but this is far from an area of expertise for me.

If it matters, I do have a signal generator and a  Fluke 87V.

Thanks
Mac

Consider this one also https://www.picotech.com/oscilloscope/2000/picoscope-2000-overview
100 quid

we have two Digilent Analog Discovery 2 and one Rigol DS1054 at work.

The Digilent is interesting it have spectrum analyzer, wish is cool but you can´t do Maths on that( that would be even cooler)  but I don´t see any shielded components inside.  so it could pick noise.  Also is good as Digital analyzer.

the Rigol work well.
I tend to work on the rigol. younger engineers prefer the Digilent. 

I like analog oscilloscopes to see analog signals.  That makes me old?

I would say that any decent oscilloscope should be enough for trace audio.
even a calibrated sound card could do the job.