Young fly-half James Hook bagged 18 points in his senior debut to help the Welsh All Blacks to an unbeatable 33-10 lead at the break. Neath ran in seven tries in the one-sided match and are on target to go one better than last year's runners-up finish in the League.
Defending champions Newport beat Caerphilly 31-13 at Virginia Park, while Carmarthen Quins travelled to Sardis Road to hand Pontypridd a surprise 23-0 beating thanks to the trusty boot of Aled Thomas (18 points).
Llanelli replacement Tomos Marks kicked an 87th-minute penalty goal to give his side a 15-12 win over Llanharan at Stradey Park, and Bedwas hammered Llandovery 42-12.
Swansea fly-half Luke Richards supplied 21 points in his side's come-from-behind 31-18 win over Ebbw Vale, Cross Keys sneaked home 16-11 at Pontypool and the Aberavon Wizards were impressive in their 38-21 at Newbridge.
Welsh Premier Division Results:
Caerphilly 13 Newport 31
Llandovery 12 Bedwas 42
Llanelli 15 Llanharan 12
Neath 48 Cardiff 24
Newbridge 21 Aberavon 38
Pontypool 11 Cross Keys 16
Pontypridd 0 Carmarthen Quins 23
Swansea 31 Ebbw Vale 18