This is a toughie as I usually take at least 15 different CDs but usually play only one track from each. In the spirit of the question I have decided to narrow it down to only 5, and I have to add that these are this evenings 5 CDs. Tomorrow the list will be totally different as I remember other favourites and just where I left my Led Zep CDs.
Loretta Lynn, The Van Lear Rose - Great Jack White production and hard rocking mixed with soft C&W. I usually listen to this first in the auditioning room.If the high end is mincing your ears then look elsewhere.
Nitin Sawhney, Beyond Skin - The music is a bit on the contrived side but the bass is about as low as I have heard and there is masses of detail. If the system can't punch you in the guts then it just aint shifting enough air!
Shakti, One Night In Bombay - My favourite live recording, having heard Shakti in concert this recording really does capture the atmosphere of the venue and the virtuosity of the players. Every time I hear the album I am in Bombay (Actually I saw them in Bristol, but what the heck!)
Hot Lub of Cowtown, Hot Jazz, Hot Swing, Hot Club - Need I say more, this studio recording captures the spirit of the band live. Fantastic musicianship hiding behind seemingly lightweight songs, a great production that always gets me grinning. It don't mean a thing if it ain't got that swing. No foot tapping = no purchase.
Dusty Springfield, Dusty In Memphis. A seemingly simple production, but if your system is up to it, just listen to that band, and Dusty is in fantastic voice. One of those records I return to after I have played all of those flashy recordings that make your hifi sound, well like a hifi.
I have missed out many long term favourites that make hifis sound good (Rumours, what a fantastic recording), terrible (Elvis Costello - My Aim is True, grimer than a grim thing but what great songs) and just want to jump along to (Legendary Shack Shakers- any!)