I was going to wait until I had played an up-coming open air gig with this amp before writing a review for the LD300, however I felt compelled to review it now.

I had decided that I needed a new amp after the guitarist in one of the bands I play for bought a Line 6 guitar amp (A Spider II I think. About 150W, twin speaker).

The 120W Behringer BX1200 Ultrabass I had been using was adequate for small clubs and pubs but could not hack outdoor gigs or the new volume from the guitarist.
Larger gigs I would usually DI through the PA, however this leaves you at the mercy of the soundman.

I had considered a number of bass amps:
Behringer BX4210A Ultrabass 450W - Cheap with lots of volume but too many reported problems with speakers failing.

Laney RB7 300W - Borrowed a friend's for a few gigs and wasn't impressed. Maybe it was just his amp but when I cranked the volume the speakers distorted badly.

Roland D-BASS115 300W - This one really caught my eye, but was way outside my budget.

Ashdown MAG-C210T-300W - Almost bought this, but the Line 6 won, why?

The LD300 definitely has all the things I need for the playing I do (I use a Yamaha BBG4S 4-string active bass).

The different amp models available are very respectable.
I play for a few cover bands that play a wide variety of styles, from 1930's to present day. The ease with which you can change the whole sound of your bass to something appropriate to the music is stunning.

The great thing about the LD300 is if you are a plug in and play type person there are already three instantly usable preset buttons on the amp (the fourth is the synth bass, which I love but isn't everyone's cup of tea).

If you want to spend a little more time you can manually change the amp sounds and play about with the tones a bit, or if you are into your effects there is plenty to be getting on with.
(I have an octaver on the BX1200 but the Octaver on the LD300 is in a different league.)

The 15" speaker can truly handle the really low bass notes and keep them clear.

Having a switchable horn on the amp was another reason I bought it. It does make the hissing louder at the high end of the volume, but if you are having to have your amp at that level then I doubt you would notice. I did this in a silent room at home to check the background noise.

The only repeated complaint I had seen about the LD300 was its weight and it is heavy compared to my old BX1200 and the RB7, but then it wasn't as heavy as I was expecting.
The thing is, an amp of this size and power is going to weigh a bit and is to be expected unless you have the money to buy a Roland D-BASS115.

It does have side handles, but the problem with these are that if you are carrying the amp on your own they make it easy to scrape your knuckles going through some doorways.

In a studio setting (DI) I got the best sound I have ever had. Usually getting the bass to sound sweet took a little while, but with the LD300 DI to the desk it was there instantly, it meant I could just relax and get into the music. The time saved was then spent playing.
(The quality of the sound pleased the engineer too.)

I could write so much more about this amp, but then there are lots of in-depth professional reviews on-line of the LD300 that state the case better than I can. (The Line 6 web site has a series of clips showcasing the amp)

Buying this amp was a major purchase for me and one I deliberated over for many months.
I needed something with lots of volume, good sound and build quality, DI and value for money. The LD300 exceeded my expectations, it has given my bass playing a whole new lease of life.

My only complaints would be the hiss at high volume and having 'fold up' handles instead of recessed ones (however, if two of you are carrying the amp, 'fold up' handles are easier than recessed ones).
Minor points really compared to the plus points.

I have owned this amp now for a few weeks. The volume is unbelievable! I have not yet managed to go much above half volume, because the whole room shakes! It is really useful having the (very accurate) tuner and compressor built into the amp - saves time and effort. I really like the variety of tones this amp can provide - any sound you want is pretty much available. The synth is fun too!
Highly recommended - feels very good quality.

I have owned this amp now for a few weeks. The volume is unbelievable! I have not yet managed to go much above half volume, because the whole room shakes! It is really useful having the (very accurate) tuner and compressor built into the amp - saves time and effort. I really like the variety of tones this amp can provide - any sound you want is pretty much available. The synth is fun too!
Highly recommended - feels very good quality.