I see it more akin to adjusting your suspension settings to suit the quality of the road surface that you're on. Most headphone users will EQ their cans, some even have genre or song specific EQ to compensate for issues with the original production, or to boost/cut frequencies that are predominant in a given genre. I also have a pair of M50X's that have to be EQ'd when listening to heavy electronic music as you can't hear yourself think! That is totally down to the amount of compression used in EDM/dance/IDM, which is used to make the recording sound better and louder than it needs to be. Some producers/sound engineers did a fantastic job (check out pretty much any Steely Dan album), and others seem very lazy.

Have you not had any success with EQ? I run the DSR7bt, and I find them to be very clear with good defined bass, but not lacking in any way. I believe they have the same drivers as the MSR7b, but it's all digital drive, with no DAC involved. Bluetooth needs EQ, but when USB connected directly I don't have to do anything to them.

Good news! Happy holidays.

If you connect it again as a disk, do they still show? I've had devices before that store the commit changes but don't action them for some reason. That, or do you have apps already installed? The 700 only supports 4 at a time.

When your device is connected to your computer, can you see both the XAPK installer and the Tidal XAPK files in the OpenService folder on your device?

You need to install the XAPK for Tidal. Follow THESE instructions for installing the XAPK and you should be good to go.