"-the Luxman strikes that most elusive balance of transparency and musicality, successfully melding superior detail retrieval with a warmth and smoothness that encourages long listening sessions." -John Acton L-507uxII Review
The L-507 is the largest of the two blue-metered standard range class a/b receivers from Luxman. It's identical in dimensions and 5 lbs heavier than the L-505. What you get above the L-505 is more power, better volume control circuit, better interior isolation, lower distortion, and upgraded cosmetics.
For power the L-505 has 100 watts at 8 ohms, and the L-507 has 110 watts at 8 ohms. On the surface this does not sound like much, until you consider the L-505 has 150 watts into 4 Ohms and the L-507 has 210 watts into 4 Ohms. That means that as a speaker starts to demand more current the L-507 pulls ahead - a scenario would be a larger diameter bass driver speaker playing dynamic rock music or big electronica music. It's similar to say a four cylinder vs an eight cylinder car. They both accelerate ok in a straight line but go up a hill with passengers and the torque of the eight cylinder won't struggle.
For volume, the L-507 has the higher level LECUA 1000 volume control which is similar to that found in the separate Luxman preamplifiers. This will give you better resolution, blacker backgrounds and a cleaner sense of musical drive. It also results in lower measured distortion, as you can see in the measured specifications. Compare the internal pictures of the L-505 and L-507 to see heavier power supplies, larger heat sinks, and interior metal walls separating components.
Cosmetically the L-507 gains polished aluminum input and volume controls combined with the nicer vintage style finger-grip metal controls below. Zoom the images and you'll see.