Having built literally hundreds of boxes for woofers and some smaller ones for displays, using glue-coated crown staples, non-coated staples and finishing nails (all with air-powered guns), various types of screws and using only glue, I can say that fasteners make a difference. They not only speed up the process (using an air stapler or nail gun) but when they're glue-coated, they also maintain contact of the joined parts while and after the glue dries. Granted, a wood joint should be stronger than the wood itself but when the material is basically little chucks or bits of ground up wood, if the stresses are great enough, the material can definitely fail. Particle board can crumble and MFD can peel in layers. If screws are used, pre-drilling and counter-sinking is best, being careful to avoid over-torquing the screws. This is how it can be done without breaking out the material at the edge. A driver with a clutch is the easiest way and I wouldn't bother to do it by hand. Screwing the box together without pre-drilling is the best way to cause breakouts and splitting, so it's a waste of time and materials.
Using corner clamps holds the parts together and assures a tight joint. If a 'bleb' is the little ring that protrudes around the hole after the drilling, that can be filed off easily, especially if it's on a face. If it's on an edge, it can be filed off but it's just a little more tricky on thin material.
BTW- it's quarter-round, not half-round, but it is a good way to dress up a joint. Some companies route a square-cornered groove in all corners and glue a piece of solid hardwood or some other material, sanding it smooth and barely easing the corner over, rounding it over or beveling it. All work and all add strength.
If anyone doubts that fasteners make a positive difference in a box, build one using scraps, using 12" x 12" x 8" for the dimensions. Use clamps to hold it while the glue dries and wait a day before removing the clamps. Now, rap on the larger sides with bare knuckles and listen for the pitch of the resonance. If you have the ability to measure the frequency using RTA software, do that and save the test. You will see a resonant peak in a narrow frequency range. Now, pre-drill and counter-sink some holes about 6" apart along one edge, install the screws making sure that they're not too tight (no breakouts) and rap on it with bare knuckles again and save this RTA test. The resonant peak will have shifted upward slightly. Repeat this along the opposite edge, but use 4" spacing instead of 6". Repeat the knuckle rap and save this test. The shift should be stronger this time. Repeat for each side and do the knuckle rap test for each edge. If just doing this to one face increases the resonance frequency raises it, screwing all faces to the edges will make even more difference. The added stiffness can place the resonance frequency outside of the operating range of the driver and with woofers, which deliver far more energy to what they're mounted into than mids or tweeters, this is important.
Now, knowing that nobody wants to see a row of screws along the border of the faces on a speaker cabinet can be considered 'attractive', a similar result can be had by screwing 'cleats' into the corners, from the inside. It's more work, more difficult and can be a pain, but Klipsch has done it for decades. The only place screws can be seen on their larger cabinets is on the rear panel, which is screwed into a set of cleats, but isn't glued because the drivers are usually mounted from the inside. Their new speakers with vinyl or wood laminates are made the same way as most- V-grooved with only one open corner, glued using dado joints and grooves for accepting the bracing and front/rear panels. This is done so the cabinets can be assembled quickly, not because it's the best way. Low production numbers allow for more steps but when a company makes 100K speakers annually, screwing the cabinets together isn't going to happen unless the selling price is extremely high.
A dado joint (in contact on three places with the piece being attached) is a great way to join wood without using fasteners as long as the glue isn't particularly flexible. Front and rear panels that are recessed are joined this way. If the panel is flush with the sides, it's likely that the side had a groove cut (an 'L" shaped cut that allows the face to fit into the pre-assembled box without leaving one panel off) or a cleat glued in to support the face. The large manufacturers don't normally use regular wood glue- they often use fast setting polyester, polyurethane or urea glues. Yellow wood glue works great for us, who usually make only a pair of boxes at one time unless we're making a full set for surround.
