We develop a new approach toward a high resolution non-parametric
reconstruction of the primordial power spectrum using WMAP cosmic microwave
background temperature anisotropies that we confront with SDSS large-scale
structure data in the range k~0.01-0.1 h/Mpc. We utilise the standard LambdaCDM
cosmological model but we allow the baryon fraction to vary. In particular, for
the concordance baryon fraction, we compare indications of a possible feature
at k~0.05 h/Mpc in WMAP data with suggestions of similar features in large
scale structure surveys.Comment: revised version, conclusions unchanged, 7 figures, accepted for
publication in MNRA