I've been following this topic - NXT Bass - for a while.
I took delivery of a black one yesterday. While I don't consider myself an upright player, I have had various uprights over the years and have utilized them a bit.
My last EUB was a Clevinger 6-string. Just too big for me, so I sold it - years ago.
Anyways, I was ready to get the WAV 4 when I heard the NXT was soon to be available. Then I came across this thread. Next, I contacted Gollihur, talked with Mark, then made the purchase.
I am very happy - 24 hours into the instrument. I am glad I don't know enough about strings to want to remove the stock strings. They are just fine.
I am posting a couple audio files for those interested. I plugged the NXT (with the volume and tone knobs full open and the switch in the down position) into a Fishman Pro-EQ Platinum Bass. The EQ setting on the Fishman is set to emphasize the bass (bass-to-treble sliders appx +9, +4, +3, +2, -1). The compression is at 10 o'clock, depth at 2 o'clock. The Fishman is plugged into an A/D. No other EQ was used.
Having said that... the tonal variations available are infinite with the combination of what's on the bass and the Fishman. I HIGHLY suggest using a preamp with this instrument.
This is a 'balanced' mix:
NXT Demo A
This mix features the bass:
NXT Demo B