Veteran Beastie Boys members Adam Horovitz, Adam Yauch and Mike Diamond are all respectably pushing their mid-40s. They’ve enjoyed more than 20 years of critical applause and commercial success over their flippant brand of Brooklyn-bred, punk rock-inspired hip-hop, and they’ve managed to properly deliver rapidly changing experimental styles with every handful of albums.

Deemed by some as a back-to-basics masterpiece and by others as a feeble and silly attempt at reliving their young-and-wild glory days, the last album “To The 5 Boroughs” at the very least succeeded in lowering the always-high expectations placed on them. Prior, it was presumed that each Beastie Boys drop would be a radical step onward for this ever-radical outfit. The album also proved that, while a shame, very few still wanted to hear their brand of fun, informative rap anymore, especially while various other thug-life rookies were busy using bullet wounds for bravado.

But whether audiences cared enough to experience them as an actual band obviously went unconsidered. Sure, by this point, the Boys are entitled to do pretty much whatever they want, but perhaps releasing the all-instrumental “The Mix-Up” wasn’t the smartest of all possible next steps.

Here’s the concept: they’re simply muted and they have reunited with their instruments – Horovitz on guitar, Yauch on bass, Diamond on drums – to create a type of atmospheric acid-funk dub most fit to

roll joints to, and not much else.

Despite being seasoned with a thousand pow-bang 70s Blaxploitation soundtracks, swanky Eastern undertones and their familiarly fuzzy garage band rawness, “The Mix-Up” sounds like 12 semi-chic songs of extended warm-up jam sessions and maybe some potentially cool sampling material for what should have been another album of witty wordplay.

The mood is alluringly affable thanks to a slick fusion of groovy organ riffs, noodling guitars, looping basslines and sexy, systematic rhythms – the type of music that would flow nice and easy in the background on a lazy-hazy summer afternoon. Still, it’s just not very Beastie Boys. And still, it can’t be shaken that a rap group playing actual instruments is no longer the type of innovative novelty strong enough to provide as an album’s sole sustenance.

Ultimately – and somewhat unfortunately, since it seems what made them so special is no longer relevant to most – the Beastie Boys could have avoided such a forgettable musical approach if they simply threw a mic back into this meandering and often mundane mix-up.