I believe you added the second part of your post after I had responded to the first.Did you read the second part of my post as it probably means you'll have to think outside the box.
Please note the following:
When a person habituates, and I feel confident you will one day, there will be no need to place fingers in your ears to stop the low level drone you refer to. The more attention you give it the more noticeable its presence will be. The idea is to use low level sound enrichment as I've mentioned and in time your brain will learn to accept it and no longer will it be of such significance. One shouldn't try to stop the noise, as this will not help the habituation process, nor use any form of masking to facilitate cancelling it out.
Giving the headphones to your girlfriend to listen doesn't mean much. As I have mentioned many times in this forum, tinnitus is mostly mental. Learning to habituate is a process and it takes time but for most people it is achievable even when it is severe like mine. My ENT consultant and Hearing Therapist have said I have a severe form of it. It has large fluctuations in intensity: completely silent, mild, moderate and severe. It has improved over the years since I had my second noise trauma in 2008, but still take Clonazepam occasionally when it is severe. This does not mean I haven't habituated.
Please read my post: The Habituation Process as it explains it in more detail.
I wish you well.
Michael
The Habituation Process | Tinnitus Talk Support Forum