bulbelectricallightingrecessed-lightingwiring
In my kitchen, I have a number of ceiling lights that take MR16 bulbs. However, I noticed that the plugs seem to also accept another kind of bulb as well. At first, I thought these other sockets were for GU10's, but the spacing in this plug is actually wider than the two GU10 prongs.
The main reason I'm wondering is because it would be great if a larger, brighter bulb could go here as the kitchen is a bit too dim.
Picture below:
I would say pull the fixture off the beam itself and attach it in between the beams. Then you could get some track lighting that would hang down low enough to provide sufficient light, yet not drop below the beam line. Something like the picture here would work:
The first linked site appears to concern itself wholly with halogen bulbs. It claims of low-voltage halogen bulbs that, "They also produce a nicer light, with warmer, brighter and more vibrant colors."
The second site's entire argument for low-voltage light being better seems to rest entirely on how configurable and remote-controllable low-voltage lights are, as well as how much easier it is to scatter gobs of them about to achieve your lighting plans for world domination.
I am inclined not to trust the first site, because their argument doesn't make intuitive sense and they provide no citations to back it up. The second site's argument makes sense on its face.
I can't speak to halogen bulbs, but when it comes to LEDs, I would not expect any difference in light quality between a line-voltage and low-voltage LED.
I don't know of any LED bulbs that actually drive the LEDs at line voltage. The ones that you can just screw into a line voltage socket just include their own DC rectifier, the same way that CFL bulbs include their own ballast to drive the fluorescence.
I would expect you can get finer control by putting your own transformer in front of a line of low-voltage LEDs, and your resulting lighting system will probably be more efficient and flexible. (As an example, I know an LED retrofit lamp I recently installed could dim down to only 5%, whereas you might be able to dim the LEDs throughout their full range using your own transformer.)
Best Answer
Thos MR16 GU5.3 light bulbs are 12 volt bulbs. The GU10 bulbs are 120 volt. There is little to zero chance that this is some sort of "Dual Socket". And if it were, it would still likely be just a 12 volt supply.
The round things in the picture are rivets that hold the fixture together.
To brighten the fixture, I'd recommend a bright, new LED bulb. Your fixture likely has a power supply with a watt limit somewhere, if you can access it, check the largest total watts you can draw on that switch and get a bulb as close to that as possible. If you don't know the power supply rating, then just try the highest output MR16 bulb you can find anyway. They usually don't take much power. Many of the fixtures were designed for incandescent anyway.
You might already have what WAS a bright LED bulb in that socket. Over time, and this is especially true of the early models made years ago, LED bulbs go dim. They may never burn out, but they loose brightness so an easy way to fix a dim fixture is to just get a new bulb. Looks like 75 watt equivalents are available. This one is rated for 700 lumens and consumes 9 watts but you might want to look for one that is Energy Star listed as they won't go dim as quickly.