Out-half Scott Deasy scored one of the Munster side's two tries and converted them both as well as adding a couple of penalties for a 15-point personal haul.
Cross Keys are now just two games away from winning the British & Irish Cup in their first season in the competition after a comprehensive 32-8 win over fellow Welsh Premiership side Llanelli.
Cross Keys' man-of-the-match Steffan Jones scored 22 of his side's points via a brace of tries, three conversions and two penalties.
Both of Sunday's quarter-final ties went the way of the home side, too, with 2010 champions Cornish Pirates easily seeing off Championship rivals Nottingham, while Leinster 'A' ended Pontypridd's hopes of a British & Irish and SWALEC Cup double with an equally comprehensive victory.
Completing a very memorable weekend for Irish rugby, Leinster 'A' beat Pontypridd 32-0 thanks to a brace of tries from outside centre Brendan Macken and further scores from flanker Conor Gilsenan and winger Darren Hudson. Noel Reid added 12 points from the kicking tee.
The semi-finals will take place over the weekend of April 6-8. The draw will follow in due course.
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