@willemj
Subwoofers are hard to do well and 8 inch woofers are rather small for that application. Room modes are certainly part of the usual problem. If you have a chance - try a JL subwoofer before buying another PV1D - you may find it integrates better. B&W make superb products but they are often bass heavy and resonant. An important factor in subwoofer design for audiophile high fidelity quality is group delay - hardly anyone measures or quotes this but I have seen measurements for JL and they are superb - measurements for many other subs I have seen tested were terrible (primarily because higher output is achievable at the expense of high group delay)
Subwoofers are hard to do well and 8 inch woofers are rather small for that application. Room modes are certainly part of the usual problem. If you have a chance - try a JL subwoofer before buying another PV1D - you may find it integrates better. B&W make superb products but they are often bass heavy and resonant. An important factor in subwoofer design for audiophile high fidelity quality is group delay - hardly anyone measures or quotes this but I have seen measurements for JL and they are superb - measurements for many other subs I have seen tested were terrible (primarily because higher output is achievable at the expense of high group delay)