Increasing the default NM on a 7800DXL

[alsoknownas]

I'm thinking of changing my trusty but ageing 7800N for a 7800DXL.
My line is subject to large (order of 6dB) reductions in noise margin overnight.
With the 7800N I can set the default NM at 9 dB and it stays connected for weeks.
I've seen plenty of stuff about reducing the default NM on the DXL but nothing about increasing it.
Can this be done and if so what are the figures ?

[billion_fan]

I'm thinking of changing my trusty but ageing 7800N for a 7800DXL.
My line is subject to large (order of 6dB) reductions in noise margin overnight.
With the 7800N I can set the default NM at 9 dB and it stays connected for weeks.
I've seen plenty of stuff about reducing the default NM on the DXL but nothing about increasing it.
Can this be done and if so what are the figures ?

Not really had requests to higher the SNR, but a starting point would be 7 and keep raising it until you reach your 9db reading