While a long time on and off user of this head since 2008, this is my first public post of using it... so sorry about my history in advance.
Well this amp is over a decade old and never really hit legendary status like some of the Line 6 products (POD, DL4, etc). Throughout the years I have used a lot of amps, and usually had multiple amps because of all the different genres of of music I play. Almost every tube amp under the sun, and was always finding that 'tone'. On a random jam with a buddy in 2008 I ended up using his HD147 while he played drums, it was phenomenal and is possibilities amazed me. I found one several months later for a steal and ended up using it a metal act, and separately in a psychedelic ambient group. With addition of the FBV Shortboard i couldn't believe that I could use the same head for the two bands I was and ditch half my pedalboard! The following year I ended up recording a record using the head exclusively. Using various mic techniques and the stellar XLR outs, i had every tone in one head again. Fell on hard times and ended up selling that guitar rig to a friend and fell out of the need to use high wattage amps.
Fast forward almost four years and I found myself back big venues, a band that played out very consistently and in the search for that 'tone'. It was a metallic hardcore act and it had been years since I played metal and thought I would play it safe with a 6505+ and let's just say it was sold within 6 months. It constantly didn't cut it for me and the sound of the amp is beyond over used in heavy music. REALLY REALLY REALLY started to miss the sound of my old trusty HD147, and the hunt began. To my surprise, despite having a cult following dropped in value significantly... to the point where i got the HD147 and an old Flextone II cab in great condition for $280 plus tax. I went home and had the 6505+ by its side with another cab and slayed it within 2 days of dialing in sounds as I was very familiar with this head from years ago. The other guitarist in my band uses a 6505+ and my amp cuts just fine and the amps compliment each other beautifully.
Anyway... I will be here more to answer questions for people who are still users, or ones interested in grabbing one of the best kept amp modeler secrets.
Below is a video of my band If He Dies opening for Earth Crisis this past saturday with an HD147. For fans of Undying, Prayer For Cleansing, All Out War, As I Lay Dying, and Killswitch Engage.
The quality is from an iPhone 4S, not the best in the world but i think for what it is, sounds great. It was shot from my side of the stage so you hear my guitar louder, enjoy.