TLDR version:
Octa-Capture is a well designed audio interface featuring 8 analog inputs, each equipped with an XLR / 1/4" combo jack and a preamp, allowing up to 8 microphones or other instruments. The front panel user interface is brilliant and allows to adjust every setting, so it can also be set up and used as a standalone mixer, all without needing a computer. Even though the unit was first released in 2010, Roland keeps updating the drivers to support the latest OS versions. The user manual is also very detailed.
It can be coupled with one more Octa-Capture, Studio-Capture, VS-100 or VS-700, allowing to expand in the future if more ports are needed.
In my opinion this is overall a better device than most in the same category.
Full version:
I wanted to get a desktop audio interface with at least 6 inputs. I was choosing between Focusrite Scarlett 8i6 (3rd gen) and MOTU Ultralite Mk5. MOTU is highly recommended, but for an amateur like me, it just seemed too expensive. So I was almost settled on the Focusrite, when I stumbled upon the Roland Octa-Capture. Released in 2010, it might be called ancient by some (in today's world, when people change their smartphones every year or two). That's why I didn't find it on any recent article titled, for example, "how to choose an audio interface" or "best audio interfaces in 2021".
I read complaints about some manufacturers releasing new models often, and dropping support for their older models (i.e. a new version of OS comes out, but they don't update the drivers). This is not the case for Roland. E.g. their Quad-Capture audio interface is discontinued, but it still has a page on their website, with drivers available for Windows 10 / macOS 11. As a person who doesn't like to change hardware often without a good reason, I prefer manufacturers with that sort of long-term commitment to their products.
Now to the device itself. If you just compare the numbers, newer interfaces seem better in terms of dynamic range on the inputs (Roland 104 dB, Focusrite 8i6 110 dB, MOTU M4 120 dB). Output dynamic range seems good at 113 dB (Focusrite 8i6 110 dB, MOTU M4 120 dB). Personally I find that numbers are not be-all and end-all. For some reason Roland doesn't provide specs for total harmonic distortion / noise. I think Roland's specs are good enough, and it works well and sounds good (to me, a non-professional).
The device is quite large (wide) for a desktop audio interface. Not a surprise, considering that all 8 analog line inputs are XLR / 1/4" combo jacks. There is an LCD screen and some buttons and rotary encoders, allowing to monitor input levels, and adjust any setting on the device. Because of this, it can work very well as a standalone mixer. Focusrite 8i6 and bigger models can also do that, but they have very few external controls, so they have to be connected to a computer to set things up via the software control panel.
A rare feature (for an audio interface of this size) is 8 mic pre-amps on the analog inputs, with 48 V phantom power individually switchable for every input . Adjustable gain on all analog inputs is useful not just for mics, but for any devices whose line outputs are not very strong. A handy feature is Auto-Sens. You start it on for one or more inputs, then play the loudest parts on the instrument(s) connected to those inputs, then stop the Auto-Sens, and the input gains are automatically set up.
On each input, a compressor is available, as well as a reverb effect.
I found the device operation quite intuitive, but Roland also took good care of the owner's manual. It's ~100 pages long, quite readable and very detailed. I use the device with a Windows 10 laptop, as well as with a MacBook. Windows 10 downloads and installs the driver automatically when you connect and power up the device. On macOS you have to download and install the driver from Roland's website. The drivers' control panels look practically identical and are easy to use.
If more ports are needed, the Octa-Capture can be coupled with one more Octa-Capture, Studio-Capture, VS-100 or VS-700. Second device's coaxial (SPDIF) out is connected to the first one's coaxial in, the digital sync signal is provided by the second device (VS EXPAND setting: ON) which acts as the timing master.
The MIDI In/Out works well and can handle a lot of data. I have them connected to a Yamaha VL70-m tone generator, I use a software called VL-Wizard to upload new instruments to the VL70-m, it sends a lot of MIDI data, which can allegedly overwhelm some USB MIDI interfaces. VL-Wizard has settings to add some delays to slow things down - with the Octa-Capture this is not needed, these delays can be left set to 0.
While on paper (in terms of some tech specs) some modern units may appear to be better, in my opinion this unit is really great and worth considering.