If you wanted to improve things, I would go with the Singxer SU-6 with an external linear power supply upgrade. Both the Singxer and the Metrum Octave DAC have a true BNC connector (which is highly superior to normal RCA digital connectors). You can then get an amazing S/PDIF cable to drive the Metrum. I use a 2-meter Nordost Heimdall II digital coax. I have not found anything better. Though, some of the Black Cat digital cables may also be excellent.
The Singxer SU-6 and linear power supply upgrade won't be a wasted investment. You can always upgrade your DAC in the future. The Singxer is really there to make the Innous a lot better.